I got invested in the characters right from the start while viewing "Source Code". Jake Gyllenhaal is Captain Stevens and Michelle Monaghan plays Christina both passengers on a commuter train headed to Chicago. The train explodes during its route and Captain Stevens "wakes up" in a dark capsule is told a minimal amount of information and is then sent back to the exact moment in time that we first saw him on the train. We learn that Stevens is on a military mission to find a bomb that killed everyone on board and that he must also find the person who planted the bomb because they are likely responsible for threatening to explode a dirty bomb in the middle of the city.

I really sunk myself into the plight of Stevens and fell for the cute Christina not really thinking at all about the improbability of what was happening. Earlier in the movie we learn that the 'Source Code' project allows one person to assume another person's mind for 8 minutes. So Stevens takes over the consciousness of a teacher Sean that was killed during the explosion. Turns out Sean and Christina had a budding relationship and Stevens' mind has now replaced that of Sean. The whole idea is a lot like "Groundhog Day" with Stevens dying every 8 minutes and then going back to the same point to try and save the train and also thwart the upcoming bombing of Chicago. He searches for clues and mistakenly follows a couple of characters both on and off the train.

Suspending disbelief is a really subjective thing for me. Sometimes I'll allow myself to accept the most ridiculous premise and other times I'll question everything going on with a roll of the eyes and an accompanying groan. But in this case I got myself caught up in the building relationship between the two main characters and I actually enjoyed myself. Then things started to fall apart.

I first got miffed about what is now a growing Hollywood cliche. The terrorist who planted the bombs is a white male who is trying to "reduce the world to rubble". He's obviously an anti-Government wacko in fact a patriotic wacko because when Stevens finds the terrorist's dirty bomb it's in a red white and blue trunk. Stevens remarks "very patriotic". Ugh...could they have presented a safer more politically correct bad guy? This snapped me into a more critical mindset and I started wondering if Stevens has 'become' Sean he would only be able to know what information Sean's experienced about the train. Sean was a teacher a simple passenger yet somehow Stevens knows damned near everything about the train. He also leaves the train to follow a passenger he first suspects. Could he do that if Sean hadn't done it previously? Where is all of this information coming from?
We've also learned that Captain Stevens actually died in a mission in Afghanistan but he's in a sort of coma that is allowing his mind to be used for the Source Code project. Stevens also learns of his condition and struggles with it while still acting as Sean the teacher and trying to find the bomber.

Stevens eventually figures out who the bomber is saves Chicago but loses the train to the first bomb. Heartbroken Stevens pleads with Source Code's controller Goodwin to allow him to go back one more time to save the train...and Christina. After 8 minutes he instructs Goodwin to basically 'pull the plug' and allow him to die. She complies and Stevens successfully saves the train and has a few last moments with Christina. He asks her what she would do with her last minute. As final seconds of his last 8 minutes ticks away he kisses her the Source Code clock expires and everything on the train is frozen in time. Stevens' last moment shows him kissing Christina. He has died but has saved the train and her life. It's a touching way for our hero to enter eternity and a very good but bittersweet ending.

Then a terrible thing happens...the movie continues and breaks all of the rules its worked so hard to establish. I'm not going to explain what occurs in the last 10 minutes other than to say it's either to give us an entirely happy ending or to set up a sequel. I can almost excuse the possibility of a lead in to a sequel business is business. But I think this travesty of a tacked on ending is due to Hollywood and it's mostly thick-headed customers needing a totally happy ending.