This was the best episode of the show. It really makes you think about whether they need to kill the person who found the cure for cancer to save all of humanity, or know that they can find a way to prevent the virus because they know it is coming.
This is by far one of the best episodes. I love that the guy comes from the future with his "sphere". This episode was very well written and I would recommend this episode to any one who ever watched the show, likes science fiction, medicine, or the idea of time travel. MUST WATCH!!