When Fry shows up late to work, the Professor forces Fry to join him and Bender in their forward time-traveling machine.  They end up going too far in the future, causing Fry to miss his date with Leela.  We get to watch an alternative universe where the guys are gone and Leela runs things.  Meanwhile, the guys continue going forward until they can find a backwards time machine but end up going to the end of the universe.  From there, the world ends up resetting and they just head forward until they find the exact point in time before they left, killing the "new" versions of themselves.