Now that both the "Harry Potter" and "Twilight" series have wrapped up, there's a franchise-sized hole in many people's lives -- and studio executives are feeling the withdrawal just as much as fans. So the hunt is on for the next big young adult series, and "The Mortal Instruments: City of Bones" is among the latest contenders.

With a 6-book series by author Cassandra Clare (not including prequels and planned sequels), "The Mortal Instruments" certainly fits the criteria: there's romance, a supernatural element, lots of action. It's a franchise in the making if all goes well, but director Harald Zwart and the rest of the cast and crew for "City of Bones" are taking things one step at a time, knowing that if they don't get the first one right, they won't get a chance at a second.

For the uninitiated, "City of Bones" follows Clary (Lily Collins, daughter of Phil), a seemingly ordinary teenager whose life is turned upside-down when she discovers a world of demons, runes and a secret cadre of warriors called Shadowhunters existing alongside our own. After her mother (Lena Headey) gets abducted by a demon, Clary joins up with a group of Shadowhunters, uncovering secrets about her past and place in this mysterious world along the way.

Moviefone visited the "City of Bones" set in Toronto, and while it doesn't hit theaters until August 23rd, we've got a wealth of exciting info to share on the film. Here's what we learned from our tour, and everything fans and non-fans alike need to know about the big-screen adaptation of the young adult bestseller.

Keeping It Real Even though "City of Bones" takes place in a world where demons, werewolves, vampires, faeries, and warlocks all walk the streets of New York City unnoticed by humans (totally plausible), the filmmakers wanted to make sure this secret supernatural world-within-a-world feels real to audiences. The film follows Clary's discovery that she's able to see this alternate New York, called Downworld, and its inhabitants, even though no one else can, gradually introducing audiences to this fantastical world.

Said producer Robert Kulzer: "It's this slow progression of taking the lead character, and hopefully the audience, from a here-and-now present day urban environment into this really, really fantastical world. Both worlds kind of coexist."

But rather than let loose with the CGI, director Harald Zwart attempted to ground "City of Bones"' fantastical elements in reality, not only for practical reasons (like keeping the budget from skyrocketing), but also to ensure the story stayed accessible to audiences, and that means playing up on the emotions more than the monsters. Lily Collins explained, "What they've done with this project is really acknowledge the fact that it is such a fantasy world, that if we don't make it real in some way, you're going to lose the audience in the CGI stuff."

"Harald is the ultimate director for this project, because it's not really his genre -- he's all about character and emotion," Collins continued. "He's made it a story about real people in this fantasy world."

Still, that doesn't mean "City of Bones" isn't suitably epic. "No one's going to be disappointed in the scope of this movie," promised producer Don Carmody.

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Yes, The Movie's Got Romance One of the big keys for Zwart was also one of the main reasons some are so quick to compare "The Mortal Instruments" to similar YA franchises like "Twilight." "At the core it's a love story," said the director, referring to the central romance, a love triangle between Clary, a Shadowhunter named Jace (played by Jamie Campbell-Bower) and Clary's best friend Simon (Robert Sheehan).

And for Campbell-Bower, that's a big draw. "This is ultimately this love story," he said, bringing up the "Twilight" comparison. "That was so successful because people invested in the love between these two characters, and that's what I want them to have with this." Kulzer agreed: "When we auditioned the two of them together, Lily and Jamie, we felt it very strongly. We felt like, 'Whoa, this is not acting, this is real stuff.' "

But despite her chemistry with her co-star, Collins downplayed the romance angle, saying it's "only one portion of this epic adventure. And yes, it fuels certain scenes and it's an undertone, but it's in no way a love story that has action in it. It's a full-blown action/adventure fantasy film based in reality that has this romance in it."

But It's Also Action-Packed From our brief time on set, we got to witness some of that action, including a few painful-looking takes of the actors throwing each other around and slamming into the furniture. A tour of Clary's house offered more hints, with breakaway glass built into one of the bedrooms, and padded tiles in the kitchen so the actors can safely slam into them.

But don't chalk it all up to movie magic, according to Collins: "With a lot of the stunt stuff, something is bound to go a little awry, and most of my reactions have genuinely been me saying, 'Ow' and screaming. When I was carving this rune in my hand, the machine that had smoke coming out started to burn my skin. I started yelling 'Ow! Ow! Ow!' but I didn't stop the take."

Still, Collins said she loved getting to do the action scenes, despite experiencing a little collateral damage: "I've gotten so many bruises at four in the morning, all hours of the night, so it's been an intense ride, but it's been really fun."

"Harald was like, 'I don't want any wires; I don't want any wire work. I don't want that. I want it to be very much if you're going to do something, if you're going to do a flip, then you need to be able to do a flip. If you're going to do a jump, you need to be able to do a jump,' " explained Campbell-Bower.

So he put in months of intense, physical training in order to handle his action scenes. "Learning how to do flips onto tables off the mini-tram was really exciting because that's me doing that in the movie. That's nobody else. That's not a facial placement. There's no wires there," Campbell-Bower said, clearly excited. "That's me jumping from the floor onto a table doing a flip in midair, which I know sounds really stupid, but the 14-year-old boy inside me goes, 'That's f**king awesome. That's so cool!'"

And Jared Harris ("Mad Men"), who plays Hodge, a former Shadowhunter-turned-tutor, can't wait for his turn. He joked, "I can still kick ass, man." Harris said of his fight scenes, "We're just practicing them now. But what's great fun is I get to fight Dredger from Sherlock Holmes [Robert Maillet]. He's a f**king enormous man."

"When you do all these fight scenes, you try and jazz 'em up and everything," he continued. "And then I sit there and I go, 'Listen, if this guy hit me, I'd collapse. I'd crumble if he actually managed to actually connect with me, because the man's huge.' "

The Plot Will Keep You on Your Toes As if stunts weren't enough for Collins to have to deal with, she also has to contend with a plot that's constantly throwing new (and shocking) revelations her way. Said Zwart, "We were joking with Lily she has what she calls 'Oh my God moments' every single day, where people give her a piece of information that turns her world upside-down."

"Literally every five minutes, she gets told something that she thought was true was a lie," Collins agreed. "She's dealing with creatures that she's never even believed in or thought existed. She's got this new superhero power with the runes and being able to see people that no one else can. She's a teenager growing up trying to discover herself. That's enough of a worry. Now she has to find out she's a Shadowhunter."

Welcome to The Institute The Institute is a central location in the film, a safehouse for Shadowhunters where Jace takes Clary after she stumbles into their world. And it's in this setting that Clary first begins to learn about her mother and her past from Harris' Hodge. Harris said of his character, "He's the adult who knows a lot more of her history than she does. And he's slowly sort of drip-feeding it to her, not telling her the whole story outright, so he's making her discover stuff for herself."

It's a location Harris knows quite intimately -- because he's not allowed to leave. "For his part in what's called The Uprising, [Hodge is] sentenced to remain in the Institute, and he has a curse or a spell put on him which means that he's not allowed to leave. And he's given the responsibility of teaching the young Shadowhunters," he explained.

We, however, were allowed to come and go as we pleased, and a tour of the Institute library revealed a remarkable attention to detail. Collins recalled being impressed when she first saw the set: "The second I walked on that about two weeks ago, I got emotional. It literally is exactly how I pictured it in my head."

Clearly, she's got a vivid imagination, because the library is packed with all sorts of artifacts and weapons. We were told the design team dictated the library's basic layout, and then worked with the stunt department to discuss the final positioning -- which means you just know it's going to see some serious action.

Cassandra Clare Is on Board For most big-screen adaptations, once the book rights have been purchased, the author's involvement is over. But the filmmakers thought it was important to keep Clare in the loop. For Kulzer, including Clare was a no-brainer, "I just felt like she made up this world, she invested so much time and energy, make her part of the decision-making process. So far, it's been great. She will say, 'I understand you make choices but I know the fans won't like this.' "

"There's people who say, 'Oh my God, don't bring in your author, you're creating a monster.' We never want to be in a situation where, one tweet and she goes, 'Robert Kulzer and Don Carmody ruined my movie.' If she does, I want her to say, 'Robert Kulzer and Don Carmody and I ruined my movie,' " laughed Kulzer.

Zwart agreed: "Cassandra's really flexible with her material. She sees that as long as we keep her intentions and what she knows that the fans love, she's been very cool." And for Zwart, she proved to be an invaluable resource whenever he's gotten stuck, "I've been emailing and calling her a lot where I've been going through the movie and I've said, 'Can you come up with a different solution of how to do this? Because I can't shoot this or it doesn't work.' She writes me pages. So that's been really great."

Still, having the author on set sometimes comes with unintended consequences -- namely, with actors angling for inside info (and spoilers). "The series isn't finished, so what they'll often ask about is what happens to their character, how it finishes up, do I die?" Clare laughed. But she holds out: "Sometimes I'll tell them things that are relevant to their characters that are either part of my notes that didn't make it into the book, or something that happens in a book that's not out yet, but I don't tell them if they're going to die."

For Clare though, being on set was a lesson in letting go. "I do come in here and I see then making paintings, and I see them building sets, and I keep wanting to thank them for doing all this. This is a huge favor to me in which you build these beautiful sets, and beautiful people come and act scenes from my books, and then I remind myself that this isn't actually about me in any way," Clare said. "This is an artistic interpretation of my books, and that's the director's vision and the actors' vision. And they have to do what they think is right."

But Collins, for one, was glad to have her there: "She's the creator of this fantasy and it's an honor to have her here and have her blessing on things. When you're a fan of something, the person that created it is the be-all-and-end-all, so it's great to have her be here and work with Harald and all the producers."

Lily's a Fan And Collins knows just how important having Clare's blessing is, because she's a huge "Mortal Instruments" fan herself. "I was actually a fan of the series before I was cast," she explained. "I've always loved fantasy books." And getting to play one of her heroes was seriously exciting for Collins: "Having read the books and being really familiar with Clary, and just kind of admiring her as a character ... I was thrilled. A fan being cast as a heroine that they admired."

Kulzer and Carmody consider themselves just as pleased to have her. Said Kulzer, "The minute she walks on the set, it's this transformation. She's totally in the zone, she's calm, she's collected, she takes notes from the director, almost like this remote engineered something. She listens to everything, hits all her marks, we just go, like, 'Oh my God, she's perfect.' "

Jamie Wants to Prove the Doubters Wrong Campbell-Bower, however, had to do a little more work to convince both the producers and the fans that he was right for the part of Jace, the film's male lead. He recalled the process, saying, "I walked into that camera test knowing that I wasn't necessarily the person that they wanted to go for and that's a hard room to walk into. That's f**king tough."

Luckily for him, he connected with his prospective co-star right away. "Lily and I just automatically clicked and these two characters just came out of us and it was like we had known each other for years. It was so weird," said Campbell-Bower.

Collins agreed, "He left and I just turned to everyone and was like, 'I really don't know what else you could be looking for. That's Jace.' "

The feeling was mutual for Clare, who said that after watching the audition tape, "I just started to cry, because I was like 'Those are my characters!' It was perfect. So from then on I was completely cemented with 'I love Jamie,' and didn't want anybody else."

But Clare's fans have been a harder sell, complaining about Campbell-Bower's casting online. Kulzer explained, "He had a hard time because, as much as they embraced Lily and also some of the other cast members that we cast later on, the fans immediately went 'Love it, love it, love it, love it.' With Jace, they were always a bit, 'Oh, but he's not a Jace.' "

And Campbell-Bower admits he let that bother him: "I think at the beginning I was very much aware of what was being said, whether it be positive or negative; predominately negative. That's something that you've gotta deal with. I have to appreciate the fact that this is a series of books that people have already encountered and people will already have preconceived notions about who the characters are, and I have to respect that."

Still, that fueled Campbell-Bower to work even harder to prove them wrong. "Of course it affected me. I'd be a cold, heartless and self-absorbed person to have it not, but it made me want to prove to these people that say I can't do this that I really can," he said. "If I can win over 50 percent of the people who said that I couldn't do this or didn't want me to do this, then I feel like I've done my job."

Collins defended her co-star, saying, "What I'm really excited about is for all the people out there that didn't want certain cast members to be Jace or [Jemima West's] part and [Kevin Zegers'] part, I think they are going to be really surprised and really happy." Then she played her trump card, declaring, "As a fan of the series, they encapsulate every emotion I would want those characters to have."

Fans Helped Design The Look Whether they know it or not, the fans played a big role in "City of Bones"' look, right down to the weapon design, especially when it came to the Shadowhunters' gear. Clare explained, "I never really describe what it looks like, so one of the things that they did was go to the fan art and look for the repeating idea of how fans imagined that fighting gear might look. And I think that served as a kind of template for their eventual development of the gear."

Carmody said it was important for them to see how "Mortal Instruments" fans visualized Clare's concepts, and chart what recurring themes popped up. "Not that we agreed a hundred percent with it all, but it's interesting to see where they are going from a design standpoint," Carmody said. "We kind of built on some of the ideas that they put out there." So a few lucky fans just might recognize their handiwork on-screen.

Some Big Names Got Into The Fun Jared Harris wasn't the only veteran actor to let loose on the "City of Bones" set. According to Kulzer, CCH Pounder had a blast playing the demonic Madame Dorothea. "There is no visual effect in the world that can beat a good actress," Kulzer said. "It's a lot of fun seeing her kicking the ass of Shadowhunters. She does it really well. And she had fun doing it."

Clare couldn't have been happier about the results, saying, "Jared Harris is so wonderful at playing conflicting characters that I felt that he would be a great Hodge. He doesn't look exactly like the character described in the book, but that doesn't matter to me as much as the fact that I feel that he can really pull that off."

Of course, one of biggest parts went to a great actor as well: the villainous Valentine Morgenstern, who's played by Jonathan Rhys-Meyers. And while he cuts an imposing figure with his tattoos and goatee (less so with the braided ponytails), he's quick to keep things light the second they call cut, to make sure Collins doesn't "hate him after two weeks."

It doesn't sound like she does. Collins said of her co-stars, "With this movie, all the cast have an amazing rapport. Even someone like Jonathan, who is so incredible and so intense and so seasoned, he still likes to have fun as well. And that makes it a really group experience and very family-like."

Sequels Will Have To Wait But even though "City of Bones" has the potential to spawn at least five sequels, the cast and crew are taking a wait-and-see approach to any future installments. The best way to ensure a second try, they figure, is to make sure that the first movie is satisfying on its own.

"Unless this movie's great, there is no franchise," said Zwart. "The book is very cleverly set up so that you almost have to read the second book in order to get answers to a lot of the questions that are raised at the end. We've been really working hard on making sure that the movie at least had an emotional closure to it."

Campbell-Bower agreed, "If it goes for another two, if it goes for another three, however many, that's great. But right now we're focusing on this one and doing this one and getting that as good as I can make it."

In other words, "City of Bones" is doing everything it can to ensure the fans go home happy, including courting Clare's blessing and keeping the essence of the books intact, even if a few details change here and there.

"The Mortal Instruments: City of Bones" is slated to open in theaters on August 23, 2013. %VIRTUAL-MtGallery-236SLIDEEXPAND--281036%
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The Mortal Instruments: City of Bones
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