PC Richie Wyatt is on a residential street in Risca, Caerphilly, after a powerful sports motorcycle collides with a brick wall. Two men were travelling on the bike at the time, and they have both been seriously injured. Close examination of the damage to the bike reveals the dynamics of the collision, but it's not proving straightforward to establish why the rider lost control.

In Chepstow, air ambulance doctors are treating a seriously injured woman after the car she was travelling in collided with a stationary lorry. She has been cut free from the wreckage, but as Sergeant Bob Witherall arrives at the scene, the damage quickly reveals the true extent of the impact.

Sergeant Cath Raine is on duty when a woman riding an electric scooter is seriously injured in a crash on her way to work in Newport. She's been struck by a car, and with the driver under arrest, all eyes are on Cath to work out what's happened. But when it emerges that the collision has been captured on camera, she's making no assumptions and insists that all viewpoints are considered.

When a crash triggers an automated call from a tourist's motorbike, paramedics and police are quickly alerted to their location in Raglan, Monmouthshire. As the seriously injured rider and pillion passenger are on their way to hospital, PC Richie Wyatt arrives at the scene. But the challenges posed by the tight bend of this slip road mean he's no stranger to investigating here, and the pressure's on to find new evidence relating to this latest collision.