1957, south-east suburbs of London. Jean Swinney is a journalist on the local newspaper, caring for her truculent mother and - unmarried in her mid-30s - considered a spinster of her parish. This limited existence of tedious chores and small pleasures is suddenly cracked open when a reporting assignment takes Jean into the intimate lives of the Tilburys: Gretchen Tilbury has made the sensational claim that her daughter Margaret is the product of a virgin birth and Jean is determined to uncover the truth. But as the initial medical tests seem to confirm Gretchen's version of events, Jean is surprised to find her life has become strangely (and not unpleasantly) intertwined with that of the Tilburys: Gretchen is now a friend, and her quirky and charming daughter Margaret a sort of surrogate child. But it is Gretchen's husband, Howard, who exerts the greatest gravitational pull on Jean: she doesn't mean to fall in love with him, but Howard surprises her with his dry wit, his intelligence and his kindness - and when she does fall, she falls hard. But he is married, and to her friend - who is also the subject of the story she is researching for the newspaper, a story that increasingly seems to be causing dark ripples across all their lives. And yet Jean cannot bring herself to discard the chance of finally having a taste of happiness... But there will be a price to pay, and it will be unbearable.