Sam is told that if he wants to go back to his regular life, he had to let Gene, et al die during a raid on a train (that's the last episode's major invest.) During the raid, there's a gun fight, the squad is out of ammo and has people injured and Sam leaves (think it was to get reinforcements or something) and he runs into the supervisor who came to cleanup the squad. He is sent back to 2005, where he wakes up from his coma. After therapy, he goes back to work but is really depressed. He zones out at a meeting and afterwards leaves to go up to the roof of the building, where he agonizes some more, etc.



And then, he gets a big smile on his face, starts running and jumps off the building! He lands, dies and returns to the exact moment he left in in '73. He runs in, saves the day, the squad is still working together after that, driving off on investigations all happy, etc.

I liked the ending - was it really time travel, was it all in Sam's head? You never really find out. From the time he steps on the roof to the time he lands was just stunning for me. It felt so depressing, but so right at the same time.