"Here you go, buddy." After a shower and a surreptitious peak into his son Indio's room (basically a holding cell for the teenager's growing guitar collection), I join Downey at our table for two on the third floor. "These should sort you out." Next to my chair are three packages: the first, a rucksack-sized packet of Epsom salts (weird, I say, as that's the sleepy suburban town where I was born; although I begin to notice weird Klingon mind-sifter moments like this happen around Downey all the time) and two small boxes of Arm & Hammer baking soda. What am I going to do with these? Bake a cake? "You have a bath back at your hotel?" he asks. I do. "Run warm water and empty everything into the bath and then get in. I wouldn't stay in there for any longer than ten minutes." Why not? Downey leans forward and taps the packet of salts in front of me. "Powerful laxative, dude."Although the consummate host and a killer gym buddy, the reason we're both sitting here is for the release of Due Date, out this month. It's directed by Todd Phillips, the man responsible for The Hangover, a movie that this summer became the biggest-selling comedy DVD of all time. Although Due Date features a cameo from gnasher-flasher Jamie Foxx (last seen with Downey in Matthew Vaughn's The Soloist, a film about a homeless violist that accumulated some significant pre-Oscar heat in 2008, only to misfire when someone actually saw the thing), the true co-star of this project is, unsurprisingly, Zach Galifianakis, the laugh-until-you-wet-yourself "reh-tard" from The Hangover; a man who's part grizzly hobo, part Curly from The Three Stooges.
Due Date is basically a buddy movie, or as Downey puts it, "like the modern, next logical step in a not-too-realistic-but-definitely-natural evolution of two schmucks on the road." Downey plays fast-talking, uptight rage queen Peter Highman, an architect who is jetting back from Atlanta to LAX so he can be at his wife's side at the birth of their first son - in a nutshell, the straight guy. Galifianakis plays Ethan Tremblay, a gay, out-of-work actor with an air-dog who's heading to California to be discovered, or as is more likely we discover, be forgotten and end up smoking his own weight in weed between bussing at the local Jack In The Box. The pair, their opposing lifestyles, opinions and hygiene habits crash headlong into each other at the airport, after which they are both escorted off the plane by an air marshall with a Taser and, now banned from American airspace, forced to make the 2,000-mile, journey together in a cramped, claustrophobic hire car. As is expected, carnage ensues, as Tremblay's chaotic, stoned manner and inability to stay awake at the wheel leaves Downey's character broke, busted, bruised and finally - this is Hollywood, remember - reborn. The movie is cut from a very similar comedic cloth as The Hangover - Phillips will do for early-thirties frat-boy humour what Judd Apatow did for twenty-something languid stoner bros.
Unusually for Downey, his role is to anchor the scene rather than blow its wheels off. It's an odd fit, especially considering Downey's last play-for-laughs part that had him black-up for the deliciously controversial role of Kirk Lazarus in Tropic Thunder, a part that still makes the actor, "uncomfortable, and weirdly apologetic". Here Galifianakis is the one allowed to get creative and punch an anarchic hole through the set.
"It's kind of embarrassing to say this," agrees Downey, "as I always thought of myself as being that type of an actor, but Zach is probably one of the freest artists I have ever experienced. The funny thing for me was having the confidence to play the straight man for once, and it gave me a whole new set of insights into the people whose responsibility it is to hold the mooring lines while the other great talents have chewed up the scenery - and I've been that guy. "