Due Date (15, 95 mins)

Alas lightning doesn’t strike twice because Due Date takes a simple premise and goes nowhere with it as the two lead characters travel thousands of miles on a journey of self-discovery.

Four screenwriters attempt to marry slapstick with soul-searching, dealing awkwardly with bereavement and the fear of impending parenthood as the film journeys from Los Angeles towards an obvious emotional crescendo in Atlanta.

If the lead characters were more clearly defined, and indeed even likeable, we might be willing travelling companions on this odyssey.

However, not even the impeccable comic timing of Galifianakis and co-star Robert Downey Jr can spark the dull dialogue to life or compel us to care about the two mismatched men as they careen from one outrageous misfortune to the next.

Expectant father Peter Highman (Robert Downey Jr) is a workaholic, who keeps in touch with his pregnant wife Sarah (Michelle Monaghan) via his omnipresent mobile phone.

With her waters expected to break in only a few days, Peter prepares to fly home to make sure he is at Sarah’s side for the birth.

A bag mix-up with fellow passenger Ethan Tremblay (Zach Galifianakis), an aspiring actor who carries his dog in his hand luggage, leads to both men being thrown off the flight.

In the absence of his passport or wallet, Peter reluctantly accepts a lift from Ethan and his pooch, who are travelling to Hollywood to seek fame and fortune.

“I’ve got 90 friends on Facebook... 12 of them are pending, but I got 90,” smiles Ethan by way of reassurance that he is a nice guy.

The aspiring actor quickly grates on Peter, leading to interludes with a drug dealer (Juliette Lewis) and a Western Union agent (Danny McBride), who turns out to be a wounded soldier from the conflict of the Middle East.

Eventually the father-to-be snaps - “I’m leaving you here because I hate you on a cellular level!” - but the film demands the healing of wounds.

Due Date delivers 95 minutes of missed opportunities, including the pointless introduction of Peter’s good friend Darryl (Jamie Foxx) so the two men can procure a new car.

There’s no on-screen chemistry between the leads and we don’t believe for a minute that enmity would mellow into companionship by the end of the trek.

A car chase across the Mexican border is preposterous and, similarly, a gross-out scene in the car late at night strains credibility.

Monaghan is stuck at the end of a phone for almost the entire film as Downey Jr and Galifianakis try to unearth just one decent laugh.

:: SWEARING :: NO SEX :: VIOLENCE :: RATING: 5/10