The hunt is on for ‘TT’ Kieron Ashton now that his identity is known, and it really is a race against time. Especially as krafty Kieron’s gone to the zoo with Karl’s family for a day of looking at monkeys and murder. What a spectacularly chilling performance Tron: Legacy‘s James Frain gives as the charming psychopath. An ordinary man behind such almost superhuman acts of terror, coolly plotting death and fear as he plays the friendly family man.

You know he’s going to kidnap Laura and the kids, and The Tunnel – which has never been one to underestimate its audience’s intelligence – knows you know.  So the penultimate episode is one exercise in torturing you up to that point and beyond, increasing the tension little by little until it’s almost suffocating.

From the investigation of Ashton’s house right through to the emotionally-draining hut scene, it is a masterful slow burn of suspense, the equivalent of (no cultural stereotypes intended) cooking a frog: gradually raising the temperature of the water until by the time it realises it’s bubbling hot, it’s too late. By the time the credits roll you feel every emotion has been boiled out of you.

Really putting a dampener on an otherwise lovely day out, Kieron lures Laura and her girls into a hut in a fort. Implausible? No more so than any other of his audacious crimes. Inside he tricks Laura into standing on a dead man’s trigger for an IED (Improvised Explosive Device/Incredibly Explodey Doohickey), then sods off, twirling his metaphorical moustache of malice and leaving Merlin’s Angel Coulby to really sell the terror of standing on a Looney Tunes cartoon-worth of explosives; communicating genuine pants-wetting horror without it feeling over the top. Can you ever be too ‘over the top’ when standing on a bomb?

And because part of you genuinely believes she might be blown to kingdom come it becomes one of those things you can’t watch but also can’t take your eyes off. Your vision becomes locked at a 45 degree angle to the screen, only half-willing to take in Karl’s emotionally-charged (potential) final moments with his wife in case what you fear is going to happen actually happens.

It doesn’t. Phew. Deep breaths. Day saved and some truly affecting performances given from the central cast. Don’t crack open that celebratory carton of fizz yet though. Kieron’s still lose, and randy mannequin and Fred from Scooby-Doo lookalike, Adam Roebuck, is about to walk right into his final trap. We might all need a stiff drink to get through The Tunnel‘s terminating episode.

Aired at 9pm on Wednesday 11 December 2013 on Sky Atlantic.

> Order The Tunnel on DVD on Amazon.

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