If you've heard sci-fi fans obsessing over Orphan Black for two years but still haven't checked out the show, this week's your chance: Amazon is making the full first season of Orphan Black free to stream on Friday. The show, a thriller about a clone trying to uncover her secretive origins, has consistently received high but tempered praise and goes into its third season on Saturday. Amazon says that the one-day-only promotion came after seeing the success of a similar promotion for Transparent. Though Orphan Black isn't Amazon's own show, it does have exclusive streaming rights to its first and second seasons, so getting viewers interested may well push Prime subscriptions. This weekend, certainly, would be a good time to start catching up.