The show revolves mostly around Sarah Manning a British born orphan who was brought to Toronto along with her gay foster brother Felix by the woman who raised them Siobhan. A former drug addict & pusher, Sarah has been away for almost a year to get away from her abusive drug dealing boyfriend Vic. On her return to the city, she witnesses a woman, who looks just like her. The distraught woman, later identified as Beth Childs, jumps in front a train killing herself, much to Sarah’s shock. Sarah however steals the woman’s purse and keys and goes to Beth’s home taking her identity along the way with the help of her brother Felix. Felix identifies the dead body as Sarah and Sarah plans to clear out Beth’s bank accounts and take her young daughter Kira away to start life anew. However she soon discovers that Beth is a cop and she is rushed to the station by Beth’s partner Detective Arthur “Art” Bell. Sarah finds herself smack down in the middle of an investigation into a shooting of a bystander and has to use her wits not to get caught.

However she soon uncovers the fact that she is one of 9 identified clones, including Beth & herself. Katja, a German clone, is killed as soon as she contacts Sarah. Sarah as ‘Beth’ soon meets Cosima an evolutionary development biologist working on her PhD from Minneapolis and Alison Hendrix, a some what conservative & tightly wound soccer mom of two adopted kids in the suburbs. The three of them with Felix form a team and try to find out about how the clones came to be without alerting their families or “monitors”. Beth’s monitor is her boyfriend Paul Dierden, an ex-military mercenary, who was contracted to be Beth’s monitor under the guise of her boyfriend. Following the discovery of Beth’s death, he finds his loyalties to the Dyad Institute crumbling, and becomes Sarah’s lover. The Dyad Institute are behind the cloning and have places monitors for each clone to report on their progress. Cosima finds out that her new friend Dr. Delphine Cormier is her monitor, who is pushed to become her lover. Delphine soon falls for Cosima as well and joins her in finding out as much as possible. Alison suspects her highschool sweetheart and now husband Donnie of being her monitor and even ties him up and briefly tortures him (without revealing the clone thing) and he denies all knowledge of being anything more than her husband who hides his porn. However in one of the final scenes it is revealed that Donnie is infact Alison’s monitor.

Art & Sarah (as Beth) investigate the discovery of a dead body (Katja) and the evidence leads them to the killer who attacks them and while Art is injured, Sarah sees that the killer is another clone – Helena, a religious nut brought up by Tomas, an ex-Dyad Institute employee to believe that she is the original and ordered to kill them one by one. Tomas is now part of a secret religious group, the Proletheans, who are behind the clone assassins. Sarah & Helena seem to share a connection which stops the latter from killing her clone – towards the end it is revealed that they were both born twins to the same surrogate mother, a South African named Amelia. Dr. Aldous Leekie, frontman of the Dyad Institute and the face of the Neolution movement is revealed to be the man with most of the answers and who seemed to be involved in a lot of the decision making. Additionally, Sarah’s daughter Kira catches the eyes of both the Dyad Institute and the Proletheans: she is the only-known biological offspring of a clone, all other clones being presumed sterile. The clones are given contracts to sign which states that the monitoring will stop by Cosima & Delphine find out that the clones have been patented by the institute, making them their properties.

As the season ends, Amelia is killed and both Siobhan & Kira are missing, presumed to be kidnapped as the closing scenes show a distraught Sarah screaming for her daughter. The cops discover that Sarah is infact alive and has been impersonating Beth. However it is revealed that Siobhan is a former member of Project LEDA in 1977 and could possibly have been Sarah’s monitor. Fantastic show with great acting and and great script, peppered with black humour and wit. A must watch for any tv series fan.