An ordinary journey. A shocking secret. And the perfect murder... Hattie travels on the 18.53 train home every night. She sits in the same seat, in the same carriage, and sees the same people. The unwritten rule is you don't talk to your fellow passengers, but Hattie has been watching them all for months now to distract herself from her own troubles. Then one night a commuter suddenly drops dead. And the terrible accident changes everything. In the aftershock of the tragic death, the group of strangers huddled around the two tables in carriage 3 strike up a conversation. Boundaries are shattered, connections are made and Hattie becomes tangled up in the lives of her fellow passengers as they travel to and from London every day. But Hattie has no idea what she's letting herself in for. The ordinary people on her ordinary journey all have dangerous secrets. When another commuter is killed, Hattie suspects someone in carriage 3 is responsible. Who can she trust? And is the truth closer to home and more dangerous than she could have guessed?