A police officer realises that his train may be at the centre of an international incident.

As Abby attempts to bring the train to a halt, the remaining passengers turn on Joe.

Abby and Joe are stunned to discover that someone onboard may be working against them.

With the entire network now out of control, Abby starts to doubt everyone around her too.

As Abby's interrogated by Hud, Joe is forced to work with Saj to try and stop the train.

As dawn breaks and Abby realises the truth, Joe and the others reach the end of the line.