Refreshed after a series of adverts for Gordon’s gin, Philip Glenister returns to BBC One in fine fettle as Harry Venn, a struggling solicitor with an insalubrious past, in this promising four-part thriller from Ronan Bennett and Walter Bernstein.

‘I think you’re the kind of man who finds what he’s looking for,’ enigmatic lawyer Gina Hawkes (Thekla Reuten) informs Harry after engaging him to locate someone on behalf of her client, Stevie Quick – a man currently on trial for a crime of which he is apparently innocent.

So far, so comprehensible, but it rapidly becomes clear that this is merely the tip of an iceberg of intrigue large enough to sink the Titanic… or at least, one big enough to be broken up and used in perpetuity to chill the endless sea of booze consumed throughout the episode. If you’re playing a drinking game whereby you take a sip each time one of the characters do, you’ll be on the floor after half an hour – and worse, you’ll completely lose your grip on what is a fascinating but involved drama.

Glenister is supremely well-cast and dominates the screen from the off. The boorish bluster of Gene Hunt seems a long time ago now, and despite sharing a deep-seated love of drink, women and recreational drugs with his illustrious Plod predecessor (at one point, he’s snorting coke in the squalid Withnail-ish flat he apparently shares with assistant Matt while bass-heavy European techno pumps out of the stereo; at another, he enjoys a post-coital joint with his ex-wife) Harry is a much more restrained character – Glenister rarely raises his rolling, golden syrup-and-Gauloise baritone much above a growl.

A smack in the chops from a boxer, the arrest of his son for stealing a car, even his girlfriend flashing her boobs in his office… nothing particularly fazes him. Even when he’s strong-arming smarmy jailbird Stevie Quick, he hisses, rather than, bellows, ‘What’s all this shit about my brother?’

What indeed? Although this first instalment doles out enough plot strands to keep Spooks in storylines for another ten years, the connection between the activities involving Gina and her case in the present-day and the murder of Harry’s brother and his own criminal proclivities in the past (pleasingly depicted through a washed-out, almost colourless filter to provide contrast with the scenes in the present) remains as unclear at the literally explosive climax as it did at the beginning.

As for the secondary story of political intrigue and social turbulence running in the background, well, the relationship with Harry’s story is anyone’s guess; and although there obviously is a link, one almost wishes that there weren’t.

The tale of beleaguered Prime Minister Brian Worsley’s (David Michaels) attempts to forge a coalition government feels dated and irrelevant this far into the life of its real-world counterpart, while the backdrop of public unrest – ‘Who’d have thought rioting in London would become practically a daily occurrence?’ – is so obviously inspired by the student protests of 2010 that it sits uneasily with the more recent riots and looting seen in the capital and around the country.

It’s a shame, given the impressive amount of detail put in (Adam Boulton, Kirsty Wark and Nina Hossain all appear in cameos as themselves) but it all feels a bit plastic and artificial in comparison with the principal strand of the story. Hopefully, when the separate parts become enmeshed, they’ll be as palatable and satisfying as a large gin and tonic. We’ll drink (responsibly) to that.

Aired at 9pm on Thursday 6th October 2011 on BBC One.

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