Guy attempts to set the world record for riding a motorcycle on the surface of water.
With the help of a Cambridge professor and a team of marine engineers, Guy's stunt hinges on Sir Isaac Newton's Third Law of Motion: that every action has an equal and opposite reaction.
If he can maintain enough speed on his bike, the 250-year-old theory says he should be able to achieve the seemingly impossible: to ride on water.
The team master the engineering on the back wheel and the extra fittings on the bike to enable it to skim across the surface of a lake.
Crashing is inevitable, so Guy endures a rigorous training schedule, trying to escape underwater from a submersion rig and then conducting a series of dizzying trial runs, hitting the water at 30mph head first.
The final record attempt takes place at Bala Lake in Snowdonia - which is so deep a 10-storey building could be submerged in it - with Guy surrounded by an army of rescue teams and emergency divers.
