Could CCTV reveal the truth behind a fatal motorbike crash? And after a three-car crash in heavy rain, the team are left stunned by what they discover.

A four-car crash and a multi-emergency response - the team must act quickly to piece it together. And after a single-vehicle crash on the M4 on Christmas Day, they are suspicious that there is more to it than meets the eye, and turn to science to get to the truth.

When a tractor crashes into a family car on a busy city street, officers search for the truth behind the lies and get more than they bargained for when they reconstruct the events of the night.

Following the work of Gwent Police's Collision Investigation Unit, the team are alerted to a serious crash by the latest in-car technology, and turn to 3D laser scanning to help establish the facts of what happened. And after a van crashes into a bus shelter, they must find and interpret the evidence to solve the mystery of why the driver lost control.

The Crash Detectives are called in to investigate a hit-and-run that leaves a cyclist fighting for her life, while mystery surrounds the death of a delivery driver on a busy dual carriageway.

When calls start coming in to report debris on the M4 motorway, police discover that a father and son have been in a serious crash. As traffic chaos builds, the pressure’s on for the collision team to find out why the car left the road.

When a Friday evening trip out in the car ends in a fatal crash, the driver refuses to accept his driving is to blame. The collision team must find the evidence to prove the real story of the night.

When a head-on crash leaves a grandfather dead, Chris discovers the answers could lie in electronic data within the car. As his mission to access it begins, he unearths an intriguing story of what really led up to the crash.

The collision team are called in to investigate a high-speed crash on the M4 which closes the motorway in both directions. With a driver under arrest and offering few clues, the answers could lie with a silent witness.

A pedestrian is seriously injured after being struck by a car in a residential street, but police are suspicious of the teenaged driver’s version of events. After a motorcycle crash outside a busy garden centre, the full story is revealed - by the bike itself.

It’s Friday night, and desperate 999 calls start flooding in to report a car travelling the wrong way along the motorway - but it still ends in tragedy. A motorbike and van collide in a busy city centre, but the story isn’t as clear as it first seems.

When a woman dies after being hit by a lorry on her way to play bingo, the team must reconstruct the scene of the crash to find out who’s to blame. A cyclist fights for his life after a crash with an articulated lorry.

When a man is found dead on a dark mountain road, there’s no sign of a vehicle. With just fragments of debris for clues, the pressure is on to track down the driver that’s fled the scene.

An 18-year-old man has died in a head-on crash on a country road. As word of the tragedy begins to circulate on social media, a horrifying tale of recklessness is about to be exposed.

When a motorcyclist dies in a crash at a busy city junction, the race is on to find out how the collision unfolded. A man waiting at a bus stop has a lucky escape after a driver loses control.

As two young children fight for their lives after their family car is hit by a van on the M4 motorway, the team focus on finding the scene evidence to reveal the devastating truth behind this crash.