Will Ferrell is like the North Atlantic Ocean of comedy, the link between black British absurdist humour and boisterous American slapstick. I doesn’t matter how overexposed the actor is in Hollywood, or how mediocre a number of his projects have proven to be, I can’t help but giggle uncontrollably every time he barks out another bizarre non sequitur like an uncontrollable tic.

With that in mind, it’s safe to say I was always going to like Ferrell’s latest offering The Other Guys. I am, however, disappointed I didn’t love it.

Let’s start with the good news: The Other Guys is funny. Along with not starring Tracy Morgan, this immediately gives it an advantage over this year’s other buddy-cop parody, Cop Out. Ferrell is as likeable as he was in Elf and as witty as he was in Anchorman, not all that surprising given the latter film was also written and directed by Adam McKay. As the forth film they’ve made togther, McKay is well aware that Ferrell is at his comedic best when playing a likeable nitwit who delivers, and often improvises, absurd spiels of dialogue with childish candour.

Now for the bad news: The Other Guys has a messy, semi-serious plot that struggles to keep the energy and humour levels up the more it unravels. It begins with a bang as New York super cops Christopher Danson and P.K. Highsmith (Dwayne Johnson and Samuel L. Jackson; great casting) chase down a carload of crooks with fearless stuntman heroics. If they’re the glorified face of justice, desk-jockeys Allen Gamble (Will Ferrell) and Terry Hoitz (Mark Wahlberg) are the thankless organs operating behind the scenes. It’s their job to handle all the tedious paperwork back at Police HQ while the Danson and Highsmith take all the media credit.

Hoitz hates being cooped up in the office; “you’ve got to let this peacock fly!” he repeatedly tells his distrusting Captain (Michael Keaton). Gamble, on the other hand, loves nothing more than punching numbers into his calculator – even his impossibly attractive wife Shelia (a brilliant Eva Mendes) is a distant second. The two partners don’t exactly see eye to eye, yet they must work together if they want to fill the shoes left behind by Danson and Highsmith, who are put out of commission when their egos finally get the better of them.

Thanks to the brilliant dynamic between the two leads, the first hour of The Other Guys is flat-out hilarious. This is the funniest Wahlberg’s been since he whispered to trees in The Happening, only this time we’re laughing with him. While most of the humour still comes by way of Ferrell’s incongruous outbursts, it’s the way he bounces off Wahlberg’s straight-faced bewilderment that amplifies each punch-line. Gamble’s minute-long rant about how a tuna fish could defeat a pack of lions had the entire audience in hysterics.

But just when Hoitz and Gamble’s partnership takes full flight, the plot shows up, flashes its badge and spoils the party.

As refreshing as it is to see an action-comedy with a bit more narrative depth than the generic likes of Knight and Day and The Losers, it’s important that a) it remains coherent and b) it fuels the comedy. Yet the roundabout Ponzi scheme at play – which sees Steve Coogan play a British billionaire investor who owes money to everyone you don’t want to owe money to – forces Ferrell and Wahlberg to deliver dull chunks of exposition in place of witty banter. It’s a fault of the film’s oddly serious subtext about corporate greed that starts to work its way to the fore the more the film progresses. By the time the credits roll, we’re not met with an amusing blooper reel like you’d expect, rather we’re bombarded with of startling statistics about how fat-cat executives increased their bonuses during the global recession. As much as I like a movie with a message, I’m not sure a silly Will Ferrell comedy is the best place for a staid critique of capitalism. It’s a bit like programing an election advertisement to run during Sesame Street. It just doesn’t fit.

What does fit, thankfully, is everything else.  When it’s not preaching politics, The Other Guys sees Ferrell, Wahlberg and McKay at the top of their game.

Follow the author Anders Wotzke on Twitter.