‘That’s a funny story,’ Richard MacDuff (Darren Boyd) says during tonight’s Dirk Gently. ‘Not funny ha-ha, obviously.’ And thus, he neatly sums up the principal problem with this peculiarly fascinating but ultimately frustrating episode.

Like last week’s opening instalment, it’s intelligently-plotted, well-acted and makes exceptional use of a small budget to end up looking extremely stylish. Unfortunately, unlike Episode 1, it has the same amount of actual laugh-loud moments as the pilot in 2010 – zilcho – and, worse, the grinometer rarely rises above ‘faintly wry simper’.

Oddly enough, this isn’t an end-of-days catastrophe. If Dirk Gently was simply a comedy and nothing more, it would be, and this would be the end of the review. Yet like the original source material (and apart from Dirk’s narcoleptic clairvoyance, St Cedd’s College and a few other nods to Douglas Adams, this isn’t anything like the original source material) there’s more to the show than just humour, which means that last week’s funny, clever mystery was a success and this week’s clever mystery is… watchable.

Gently (Stephen Mangan) and MacDuff (along with the latter’s girlfriend Susan, once again portrayed by Helen Baxendale) head back to the former’s alma mater in Cambridge where Professor Jericho (Bill Paterson) has employed the detective – who was expelled from the university thanks to his word-perfect prediction of an exam paper during his third year – as head of security for the Institute of Science and Technology.

Unfortunately, when the robot replica of Jericho’s daughter goes AWOL and the professor himself ends up with his head bashed in, Sherlock Holistic and Doctor Watching are the prime suspects.

Hilarity doesn’t really ensue (although MacDuff’s description of his mother as ‘uniquely unlikeable’ and the line ‘The real David Cho has gone to live with a homosexual homunculus in Humberside’ are both smirkworthy) and there’s a sombre sentimentalism to Dirk’s dismay at disappointing Jericho which sits uneasily with the character.

The subplot of MacDuff’s consternation at having to choose between moving to Cambridge with Susan or staying in London as Dirk’s partner/assistant (a running joke that’s already been lapped several times and really ought to give up) is equally unsatisfactory, as it shows him up as little more than the pseudo-John Watson we feared he might become.

If the show itself has a personality schism, unable to pigeonhole itself as either a comedy drama or drama-with-occasional-amusement, MacDuff is a crisis in search of an identity. No matter what Darren Boyd does with him, he’s a sensible, sensitive sidekick straight off the Sherlock subs’ bench and nothing more – which is a shame.

However, although excessively emotion isn’t really what Dirk Gently ought to be about, there are some authentically moving moments in the episode that fit it as unexpectedly neatly as the sight of an Austin Princess parked outside a Cambridge college. The brief relationship between Dirk and Jane/Max (the excellent Lydia Wilson) is actually quite touching, from their shared chip shop banquet to their bus stop farewell, and it’s light years away from the uncomfortable midway mawkishness earlier in the episode.

The lasting disappointment one is left with at the end of the episode is that there aren’t any uproariously comic scenes to match it.

Aired at 9pm on Monday 12th March 2012 on BBC Four.

> Buy the Series 1 DVD on Amazon.

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