Welcoming its new sister into the AMC Networks fold, IFC will offer back-to-back airings of the first two seasons of BBC America’s “Orphan Black” ahead of the sci-fi drama’s season three premiere.

The 21-hour marathon starts at midnight on April 17 and will give fans (and newcomers) a chance to follow Tatiana Maslany’s Sarah Manning from her initial discovery that she has cloned counterparts all the way through the season two finale, which ends with a shocking twist that will change the course of the series forever.

AMC Networks will air the season three premiere of “Orphan Black” across all of its U.S. networks – including IFC and BBC America — at 9 p.m. on April 18.