Benedict Cumberbatch walks into a Manhattan comic book store in full superhero regalia, magic cloak billowing behind him, leafs through a few periodicals and asks the owner for a job.

It sounds like the start of a bad joke but this episode actually happened during the final days of filming of the upcoming "Doctor Strange," the British actor revealed on Thursday.

The 14th film in Disney's "Marvel Cinematic Universe" was about to wrap and the 40-year-old was running up Fifth Avenue toward the Empire State Building when he and director Scott Derrickson spotted the store and decided to go in.

"I didn't have any money -- I offered my services. I said if the film doesn't work out I'll come and stack the shelves," joked Cumberbatch, who stars as the titular sorcerer in the movie, at a news conference in Beverly Hills.

"It was a magic, magic moment -- no pun intended. It was very special. And utterly, like a lot of things in this film, not searched for."

Derrickson recalled Cumberbatch suddenly spotting the store.

"He's in full (costume) and I go, 'We have to go in!' And he goes 'We should, shouldn't we?'" the filmmaker recounted.

"I said, 'I'll film it, it'll just be us.' So I put my camera on and he introduced himself and said, 'Hey, I'm about to go into this comic book store,' and I followed him in, and the people in there couldn't believe it -- it was Doctor Strange! And he walked right up to the Doctor Strange comics."

'Superhero moment'

Filmed in Nepal, New York, London and Hong Kong, "Doctor Strange" tells the story of world-famous neurosurgeon Stephen Strange, whose life changes forever after a horrific car accident robs him of the use of his hands.

Failed by Western medicine, he travels to Kathmandu where he happens upon a healing center which, it turns out, doubles as the front line of a battle against unseen dark forces bent on destroying reality.

The stellar cast includes Rachel McAdams, Benedict Wong, Mads Mikkelsen and Tilda Swinton, all of whom joined Cumberbatch at the news conference, as well as Chiwetel Ejiofor, and Michael Stuhlbarg.

Cumberbatch, who rose to global stardom playing the title role in the hit BBC television detective series "Sherlock," did most of his own fight scenes.

The actor said he was "giddy, like a child at Halloween" when he first donned Strange's magical Cloak of Levitation, prompting an old Marvel hand among the crew to observe "oh, you're having a superhero moment, aren't you?"

McAdams, who plays Strange's love interest, emergency room surgeon Christine Palmer, revealed that her real-life mother Sandra was a nurse.

Although she threw herself briefly into medical research, observing a neurosurgeon, she admits she does not have her mother's healthcare vocation.

'Queasy about blood'

"I was given an offer to go in an Evac helicopter and do a weekend, which I'm so sad I had to turn down because I'm a terrible flyer and I am really queasy about blood," she said.

"I thought I would be more of a hindrance to that operation than a help so I declined that. But everything else was super-fascinating and, at a pinch, I could probably suture something up now."

Swinton, who plays the Ancient One, a master of the mystical arts who trains Strange to become a powerful sorcerer, said working on a Marvel movie is "a bit like joining the circus."

"You get invited to be the bearded lady or the painted gentleman or something and you may have a chance in the future to play with a clown or learn a bit of trapeze or work with the ponies," she told reporters.

Marvel Studios boss Kevin Feige, she said, was the "sorcerer supreme," the "superfan of all superfans" and "the master of the big top."

"Doctor Strange" will be released in the United States on November 4, a full 30 years after it officially went into pre-production -- starting a process which was beset by numerous delays over the years, for all manner of reasons.

Advance tickets went on sale last week in the US, where it is expected to have the fall's best opening, predicted at somewhere between $55-$75 million.

If all goes to plan, Strange will be a big player in the next "Avengers" movie, Feige announced.

"We're thinking it one step at a time. Benedict puts on the cloak once again early next year in 'Infinity War,'" he said.