Is Cruise losing control?

"It's someone's opinion that says you have a chemical imbalance," he argues forcefully. "There's no blood test that can show there's a chemical imbalance. They can test for serotonin levels, but only on a cadaver. I'm telling you, it's that horrific, so when I think about the parents of these children who are being lied to, who are given erroneous information ... These people have set themselves up as authorities, and, basically, it is just an esoteric cult, and it's disgusting."

Steady on, Tom. Many, after all, regard Scientology itself as an " esoteric cult". But he is in full flight now, rushing on from the subject of racial cleansing in the Second World War to mental disorders that were invented to suppress people. I start to feel nervous, and not a little agitated; no amount of examples from me of friends who have benefited from therapy or Prozac will be allowed in discussion here, I can tell. I realise, when I see him on a CNN talk show with Larry King the following night, giving the psychiatry rant all over again, that it is not just for my benefit.

If Cruise can't say enough about Scientology, when it comes to his business affairs he retreats into frustrating generalisations. This is the Tom Cruise whose producing partnership with former talent agent Paula Wagner has yielded hits such as The Others, Shattered Glass and the Mission: Impossible films, in which he also stars. They have made him one of the richest men in Hollywood.

The stories of discontent on the long Australian shoot of MI:2 in 2000 are well documented, along with the film's year-long delay. Now MI:3 has hit the same choppy waters before filming has begun. Cruise and Wagner hired young director Joe Carnahan to make the movie for summer 2005 release. But six weeks before it was set to go before the cameras, Carnahan was out, with both sides citing that old chestnut, "creative differences".

A new director - JJ Abrams, creator of cult TV series Alias - has been hired but filming has been postponed until next summer. Cruise has opted instead to team up with Steven Spielberg on a new version of HG Wells's The War of the Worlds, leaving crews in Berlin who were working on pre-production on MI:3 unemployed and the cast, including Scarlett Johansson and Kenneth Branagh, with a big hole in their schedules.

"It's not Mission: Difficult, you know," Cruise laughs, fobbing off questions about the halted production.

HE appears keen not to display any signs of business acumen. Cruise, ahead of all his peers, has mastered the art of promoting his films outside the US. He stands for more than an hour in Leicester Square before premieres signing autographs, he travels tirelessly to open his movies in every major territory, appearing on chat shows, granting interviews. Anyone in Hollywood will vouch for his professionalism.

These personal appearances help the films exponentially: his last movie, The Last Samurai, grossed some $111 million in North America, but took in more than $350 million in the rest of the world, an unheard of ratio; usually it is more along 50/50 lines.

It's in his interest. When you are earning a $20 million salary plus a hefty percentage of worldwide gross, you'd want to be out there pounding the pavement. But when I ask Cruise about it, his disingenous answer is that he likes to travel.

"I always wanted to go to Europe as a kid. I just like going, it's as basic as that. I used to look at these postcards and go to the library and I was always an amateur history buff, so I always wanted to go to these places and meet these people and learn about how they live." Collateral director Michael Mann is more forthright about his star: "He's streetwise and worldwise. He's smarter about marketing motion pictures than most people working in the studios. He's nobody's fool, he's not naive."

Mann's testimony adds to the puzzle. It's an awkward new persona that Cruise is crafting. On the one hand he is still presenting a manufactured, wide-eyed image with no insight into his high-profile business life or marketing savvy. On the other, he is unstoppable as a spokesman for Scientology.

"In earlier years, he didn't talk about Scientology," his sister, DeVette, 46, who has worked with Cruise for more than a decade in publicity and marketing, tells The New York Daily News, "and everybody said he was keeping it a big mystery. Now he talks about it and it's wrong. It's damned if you do, damned if you don't." Maybe she has a point.

Collateral opens on 17 September.