Orphan Black's fourth season premieres on Netflix in the UK on April 15, just one day after the show's stateside return to BBC America.
It tells the story of streetwise Sarah Manning, played by Canadian actress Tatiana Maslany. When she witnesses lookalike stranger Beth Childs take her own life, Sarah assumes the dead woman's identity.
But by doing so, Sarah soon uncovers an earth-shattering secret - she is a clone. As Sarah searches for answers, she learns there are more like her out there, genetically identical individuals who have been nurtured in wildly different circumstances.
And someone is trying to kill them off, one by one.
Season four kicks off with Sarah reluctantly returning home from her Icelandic hideout to track down an elusive and mysterious ally tied to the clone who started it all -- Beth Childs.
Year after year, Tatiana has been hailed by leading television critics for her amazing performance in Orphan Black which has so far won her two Critics' Choice awards and a Primetime Emmy nomination. It is no easy task to play several characters, including a transgender clone, and give them all disparate traits and personalities.
Here's the lowdown on some of the clones Tatiana has played so far.
Damaged and troubled she may have been, but Beth was a cop and Sarah has grown to respect the valiant person whose identity she assumed. Beth's story is being told via flashbacks.
Alison is apparently all about domesticity. She married young and is the adoptive mother of Gemma (played by Millie Davis) and Oscar (Drew Davis). On the surface she appears to be in control, but Alison dabbled with substance abuse and drug dealing.
Cosima is gay, brainy and dying. She has a congenital respiratory illness that has killed other clones and continues to threaten her life. With her health in decline, she is driven to discover a cure to save her sisters from what appears to be their collective fate.
Introduced in the second season, transgender clone Tony was born Antoinette Sawicki and is in the process of undergoing transition. When he is later told by Sarah that he is a clone, he accepts the news more easily than she did because of his existing identity issues.
Rachel was the first female clone who was raised aware of her origins. A corporate cutthroat with a desire for power, her one weakness is a hatred of Sarah, which blinds her focus. Cold and calculated, it remains to be seen if she can become a better person.
Raised by nuns in an oppressive Ukrainian convent, Helena's abusive upbringing made her easy prey for a religious extremist cult who re-programmed her to kill her sister clones. But that all changes after she meets Sarah. After being impregnated by the leader of the Proletheans, a clone-hating cult, she escapes. But will the expectant mother adjust to her new life?