Kaye's world is shaken up when her sister Ruby returns with her boyfriend Michael. Eleswhere, as night falls, the Donahue family prepare nervously for the formidable race ahead.
London's huge wall presents the racers with another massive obstacle, while the General and Faith hatch a sneaky plan and Jenny grows increasingly anxious.
The ambulance, the hot hatch and the Volvo all chase an impenetrable Brookeheath prison truck containing some important cargo, heading towards the badlands of Manchester.
The remaining racers near the finish line as they approach the Highlands, and Kaye reveals a secret she has been keeping for years when she makes a shocking confession to Michael.