On the hottest day of the year, Caroline Harvey is found dead in Suffolk. Her body is left draped over a cot - but the baby she was looking after is missing. Hundreds of miles away, Siobhan Dillon is on a luxurious family holiday in France when her husband, Callum, is arrested by French police on suspicion of murder. As Siobhan's perfect family is torn apart by the media in the nation's frantic search for the missing baby, she desperately tries to piece together how Callum knew Caroline. What happened that night? Was Caroline as innocent as she seemed - or was she hiding a secret of her own?