On the surface, Luke and his girlfriend Hannah seem to have a perfect life. He's an A&R man, she's an arts correspondent and they are devoted to their newborn son Samuel. But beneath the gloss Luke has always felt like an outsider. When he finds his birth mother Alice, the instant connection with her is a little like falling in love.
So when Hannah goes back to work, Luke asks Alice to look after their son. But Alice - deranged with grief when her baby was taken from her 27 years ago - starts to fall in love with Samuel, and starts to pretend their child is hers...