Based on the book by Chris Cleave, Incendiary follows a grieving mother (Michelle Williams) as she attempts to come to terms with a terrorist bombing that takes the life of her husband and young son. Some have criticized the book for taking advantage of the London bombings, however it was written before that attack and even arrived in bookstores on that same day. Bridget Jones's Diary director Sharon Maguire takes the helm here, bringing us a daunting multi-layered story that begins with a bang (no pun intended), but then slowly falls apart when it doesn't have time to tie up loose ends.

The entire film is wrapped around a letter our main character, an unnamed "Young Mother", is writing to Osama Bin Laden. During a football match, terrorists set off a number of bombs and crumble the stadium. At that exact moment, "Young Mother" is having sex with someone who is not her husband; a journalist named Jasper Black (Ewan McGregor) who she meets one night while feeling alone, deflated and emotionless due to her husband's long hours on the job as a bomb expert. But it's not just his job; he doesn't pay much attention to his wife at all -- he ignores her, never touches her and has seemingly drained whatever ounce of love was left between them.

And that's the first act -- the most compelling piece of Incendiary, because from that point on there are some nuggets of gold (William's performance, for starters), but they're few and far between. Thanks to a tip from her journalist kind-of-f*ck-buddy, "Young Mother" finds out the name of one suicide bomber, and subsequently tracks down his wife and son; slowly becoming obsessed with the latter. In between that subplot, one of her husband's married co-workers develops a help-save-the-wounded-widow crush on "Young Mother" while Jasper Black continues to remain in the picture out of either guilt, love or both.

"Young Mother" jumps in and out of each side story, completely unattached to life around her. She misses her son. She regrets cheating on her husband. She asks: "Is it possible to love and betray at the same time." Though as our main character slowly loses her mind, so goes the story as well. An overly-long fantasy sequence (in which "Young Mother" becomes convinced her son is still alive and living with her) takes the place of a few plot points that needed to be wrapped up. Instead, the character and the movie just sort of disappear into this weird time-waster before we pop out into a late reveal that, like the ones before it, never gets explained.

All that being said, Williams is magnificent in her role -- though they beat the living hell out of her, to a point where it almost becomes ridiculous. Her British accent is flawless, coupled with the long hair and weight loss -- you'd have no idea it was Williams playing the part. I haven't read the book, nor have I lost a loved one in a terrorist attack, but I have to imagine the tremendous amount of grief displayed here is accurate. Another half hour to wrap things up would've been nice, but as it stands Incendiary has one of the best first acts I've seen at the festival so far. Too bad the same can't be said for the rest of it.