In Deep is an action comedy following the escapades of two hapless young police constables who go break rank and go undercover to solve the case of their lives.

Straight-laced but street-smart Nathan Fontes and maverick dreamer Jimmy Swann are languishing together on the bottom rung of the policing ladder. Adult responsibilities weigh heavily on Nathan's shoulders - he's got a young son and a fractious relationship with his ex, and has resigned himself to working his way up the hard way. Jimmy, on the other hand, is always looking for short cuts and has a romanticised idea of police work, gleaned from the cop shows he's addicted to.

When a very unexpected case falls suddenly into their laps, it's the chance they've been waiting for. Their nemesis, DCI Lehane, swiftly takes the case off their hands, but not before Jimmy manages to remove a vital clue from the crime scene. It's a chance to crack the case and make heroes of themselves. All they need to do is break rank and go undercover for just one night.

But when the wheels come off their plan, they find themselves embroiled in a sprawling mystery that goes all the way to the top. The only way out, is to go in deeper.