Sign me up! Subscribe to our drama newsletter to keep up to date with all things dramatic – from crime dramas to comedy dramas, plus television and entertainment newsletters Alexandra Roach plays Zoe Sterling Viewpoint ITV Who is Zoe Sterling? A secret voyeur and a single mother whose young daughter, Caitlin, goes to the school where missing primary school teacher Gemma Hillman teaches. Her flat also overlooks the home of Gemma and her partner, Greg, making it the perfect location for a police surveillance team. Where have I seen Alexandra Roach before? She played the young Margaret Thatcher in the Oscar-winning film The Iron Lady, and Countess Nordston in the film Anna Karenina. She’s also starred in Testament of Youth, One Chance, Killing Eve (as assassin Rhian), Sanditon (as Diana Parker), Black Mirror and Death in Paradise.