A couple buy a synthetic human, or `synth' to help around the house, but the new arrival threatens to expose their secrets. A retired engineer's paternal relationship with his own synth is threatened by a malfunction, an android and his owner go on the run, and a detective grows suspicious of his wife's close bond with her synth.

Laura is begrudgingly forced to keep Anita when she saves Toby from a road accident. George is planning an escape with Odi and Pete's hot temper earns him a suspension from work.