“Duality” seems to be happening at the present time, but with one technological achievement: cloning oneself is not just a possibility, but a reality. Glossy ads for the «replacement» process proclaim it a love affair: if you’re going to die young, «you» will still be there, ready to take your place. Your loved ones will not need to grieve. «Deputies», as they are called, are born from a single drop of saliva and spend time with the «original» during the transition period, getting to know the life of the original, with all his likes and dislikes, preparing for a possible absorption. The transition from the original to the replacement should be smooth.
But things are different with Sarah (Karen Gillan), who suffers from a mysterious terminal illness. Sarah has a boyfriend named Peter (Beulah Koale) and a constantly judgmental mother (Maya Paunio), the only two people who truly «make a difference» in her life. Sarah hides her illness from both of them and decides to create a «replacement». The sales rep brushes off financial worries: after Sarah’s death, a «replacement» will be included in the bill. When the replacement enters the room, it’s a perfect match, except for one thing. The replacement has blue eyes, while Sarah has brown. Not a problem, the replacement can wear colored contacts!
But an anomaly is a sign of things to come. Very quickly, Sarah’s replacement shows signs of unnerving ambition. She’s not just trying to copy Sarah. She positions herself better in every way. She looks at the framed photo of Sarah and Peter and flips it face down. She comments that Sarah’s clothes don’t fit her: they are smaller. She is better in bed, more adventurous. Sarah’s mother prefers Sarah’s replacement to the real Sarah. As did Peter. Sarah is thrown out of her own life.