Orphan Black Season 2
Sarah (Tatiana Maslany) meets Rudy (Ari Millen) in "Orphan Black." (Steve Wilkie/BBC America)

Orphan Black Season 3 preview: Whose side are you on?

BBC America has released its final extended preview for “Orphan Black” Season 3, which premieres at 8 p.m. April 18 across all AMC Networks—BBC America, IFC, AMC, WE tv and SundanceTV.

The sister clones of Project Leda—Sarah, Alison, Cosima and Helena (Tatiana Maslany)—go up against the brotherhood of Project Castor—Mark, Rudy, Seth and Miller (Ari Millen).

If you haven’t caught up yet, Amazon will stream the first season for free and IFC is airing a 21-hour marathon of the first two seasons beginning Friday.

The latest preview gives a quick look back at Season 2, when Paul (Dylan Bruce), an army officer working for a still mysterious military group working within the clone world, convinced Sarah’s duplicitous foster mother, Mrs. S (Maria Doyle Kennedy), to give him Sarah’s clone sister Helena.

In the new season, Sarah and her other sisters search for Helena while trying to protect their loved ones. They Sarah’s daughter Kira (Skyler Wexler), Sarah’s foster brother Felix (Jordan Gavaris), and Kira’s father Cal (Michiel Huisman); Alison’s husband, Donnie (Kristian Bruun), and their kids; and Cosima’s lover Delphine (Evelyne Brochu), who becomes a higher up at the Dyad Institute this season.

Returning costars include Kevin Hanchard as Art, a detective who worked with a now-dead clone, and Zoe De Grand’Maison as Gracie, a Prolethean escapee who married one of the Castor clones. Guest stars this season include James Frain as Ferdinand, a cleaner sent to Dyad, Justin Chatwin as Jason Kellerman, a neighborhood dealer and Ksenia Solo as Shay, a new woman in Cosima’s life.

Graeme Manson and John Fawcett co-created the show. Manson serves as writer and Fawcett directs the Peabody Award-winning drama.