Looking for your next great thriller? It’s time to investigate Oliver Harris’s second outing with Hampstead-based bad boy cop Nick Belsey, every inch the “beguiling bastard” that crime supremo Val McDermid dubbed him when talking about his debut, The Hollow Man.

Deep Shelter (Vintage Books, £12.99) opens with Belsey newly- demoted and trying to keep his nose clean. His good intentions are short-lived, however, when he’s presented with a real old school crime riddle.

He’s hot in pursuit of a car thief hammering it down Hampstead High Street (so far, so feasible), when the driver abandons the car and heads off down what Belsey knows to be a blind alley and vanishes without trace.

Never one to let sleeping dogs lie, Belsey discovers that one of the walls in the alley belongs to the opening of a tunnel deep under NW3 and on investigation discovers a stash of booze and drugs.

What could be more natural, then, for him to take his brand new girlfriend (a recent suspect herself) into the tunnel for an illicit date? And it’s then that things really take a lurch for the worse and his girlfriend also disappears.

Thus begins a juicy plot which takes Belsey on an exploration of the network of Second World War tunnels and shelters which were covertly refashioned into nuclear war command centres and a whole lot more during the 1980s.

Hot spot

So while Londoners swelter above ground in the sticky heat of summer, Belsey is in yet another hot spot juggling his suspicious bosses while tracking an opponent using the codename of a long-gone cold war double agent who is apparently holding his girlfriend as hostage while dropping all manner of nasty items off at Hampstead nick for the hapless Belsey to discover and explain to his superiors.

Officially, the search is on for the girl, whom his colleagues do not know is connected to Belsey in any way, while unofficially he is trying to piece together their part in what he realises is a much larger crime. But who really are the bad guys and what – and when – did the crime take place?

While The Hollow Man was a breathless, no-holds-barred, debut, firmly ensconced in NW3 for the most part, Deep Shelter is a more worldly and mature foray into the dark heart of counter intelligence and cover-ups and the plot, while dramatic and unexpected is feasible and brilliantly evocative.

Want a readable yet beautifully crafted thriller with original characterisation, fabulous plot and superb pacing? Tick, tick, tick. Deep Shelter will keep you guessing and turning pages right the way through.

You can meet author Oliver Harris at the launch of Deep Shelter at West End Lane Books on its publication day, March 20. All welcome and entry is free, but please book ahead via 020 7431 3770 or info@welbooks.co.uk.