Ari is the sole occupant of a long-haul research space vessel. Her life is a lonely routine, every day the same – down to the mood-stabiliser pill she takes each night, dispensed by the ship’s medical bay. When the pills suddenly stop, Ari’s subsequent withdrawals cause her to suspect she may not have always been alone on the ship. As her withdrawals grow more severe, past and present blur into one, and Ari is forced to confront what she has been hiding from herself.