As far as Marvel movies go, there hasn't been a question mark as big as the one attached to their forthcoming action comedy "Ant-Man" since, well, ever. Even "Guardians of the Galaxy," with its roster of unknown characters and tonally daring mixture of comedy and drama, had the space adventure angle to hook people and a cast of likeable and well-known actors. "Ant-Man," on the other hand, is full of unquantifiable elements and comes complete with a troubled production history that has potentially soured would-be enthusiasts. But if this new trailer is any indication, hope is not lost. "Ant-Man" could be really, really entertaining.

The trailer certainly gives us more story than anything previously released: Hank Pym (Michael Douglas), the original Ant-Man, recruits thief Scott Lang (Paul Rudd) to stop an evil industrialist named Darren Cross (Corey Stoll). In order to get him into fighting shape, he learns from Hope Van Dyne (Evangeline Lilly), Pym's daughter. (Her mother is Hope Van Dyne, who fought under the superhero alias Wasp.) Much of the trailer is given over to the training of Scott and various zippy action sequences where Scott shrinks down to the size of an ant and then returns to normal (and back again). It's a pretty great conceit, at least visually, and ends with a wonderful gag with Ant-Man and Cross, now in his own suit and calling himself Yellowjacket, fighting atop a children's train set.

Rudd looks like a perfectly charismatic action star and it's always good to see Douglas doing something outside of his comfort zone, and while the premise isn't being sold 100% and its behind-the-scenes headaches still hurt, it's hard not to be optimistic about something that looks this fun.

"Ant-Man" opens on July 17th.