12 Monkeys

A man from the post-apocalyptic future, Cole uses a dangerous, untested method of time travel to get from 2043 to the present day. He is on a mission to locate and rid the world of the source of the plague that will eventually annihilate the human race. Assisting him is Dr. Cassandra Railly, a virologist who must decide whether to do harm in order to save the world -- regardless of the fact that she has taken the Hippocratic oath. The sci-fi series is based on Terry Gilliam's 1995 film, which starred Bruce Willis as Cole.