Three-part adaptation of Agatha Christie's book. Heiress Rachel Argyll is murdered at her family estate. Eighteen months later, the identity of the murderer is thrown in doubt.

When Ellen, a successful architect in her mid-thirties, becomes pregnant, she finds maternity cover in Paula: brilliant, enthusiastic and raring to go. Ellen wants to champion her, but something’s not right. Ellen begins to fear for her safety when she suspects her replacement has a disturbing agenda. Can her suspicions be explained away as female rivalry and her own insecurity of opting out of work at the top of her game… or do they speak to something deeper?

Samantha Hunter suspects someone within the private intelligence agency she works at tried to kill her and she seeks to uncover the person behind it.