Ellie Taylor hosts the brand-new interrogation game where members of the public who fancy themselves as amateur sleuths hear unbelievable stories from a succession of 'suspects' - but only one of them is telling the truth.
To help sort the fact from the fiction, all of the suspects are interrogated by experienced police detectives.
Using tactics deployed on criminals, they dig into the stories, prodding, probing and poring over every detail, giving them the grilling of their lives from the pressure-cooker environment of an interrogation cell.
It's up to the suspects to do a convincing job of selling their story. If the contestants manage to spot the truth, they're treated to a cash prize. But if they fail and pick a fake, the fibbing suspect walks away with the money.
In the first episode, in a secret off-grid location, ordinary people tell extraordinary tales to an elite squad of police interrogators. But who is telling the truth? Only one person's story is real, while the other three are carefully crafted lies.
The watching players must distinguish the truth tellers from the big fat fakers. If they're right, they win £5000, but if they're wrong, the blagger walks away with the cash.
In a state-of-the-art confession cell, the suspects are meticulously cross-examined by professional police interrogators while the player analyses the suspects' storytelling from a secret surveillance room, aided and abetted by host Ellie. This time, four people tell a story of how they opted out of civilisation, and four more all claim to have had the worst first date ever.
Ellie is joined by amateur sleuths Karen, who's 60, from Kent, and Antony, 39, from West Sussex, who attempt to flush out the truth tellers in a bid to walk away with the money.
With claims ranging from living as an alpine goat to declaring that they joined a sacrificial cult, can they spot whose pants are on fire?
You Won't Believe This begins Tuesday 22nd November at 10pm on Channel 4.