In this darkly comedic and poignant thriller, a bisexual serial killer named Eunice roams grim northern Britain, searching for a mysterious woman named Judith while committing psychosexual murders along the motorways. Her life is forever changed when she encounters Miriam, a lonely gas station cashier who abandons her dismal existence to follow the damaged but kind-hearted Eunice. As they form an unlikely bond, Miriam tries to understand the bizarre motives behind Eunice's actions, only to find herself drawn into a world of violence and darkness that threatens to consume them both.