I just watched Vis à Vis. I thought it was one of the best science fiction episodes about an enemy in disguise I've ever seen. It started with a seemingly interesting and friendly character, Steth, and then introduced intriguing clues to the mystery. Then it turned out Steth was a thief and a truly masterful con artist, knowing exactly what to say to win people's sympathy and throw them off his trail. Many previous writers have done similar stories, but didn't have as wonderfully convincing scenes of the disguised characters lying. And the character in the end more often turns out to be an incomprehensible monster, like the Salt Vampire, but having the character be a master thief is a brilliant touch.
