A parasite causes Captain Archer to lose his short-term memory, and he (with the help of T'Pol and Doctor Phlox) seeks a way to change the past.
Air Date: 11/05/03
Director: Robert Duncan McNeill
A damned fine story with a brain-wrecking timeline twist. Still, I have said before, Trek does time travel better than any show in history...and this one is a lot of fun.