Actor Keanu Reeves was in London this week to promote The Day the Earth Stood Still, a remake of the 1951 science-fiction classic.
Best known for his roles in Speed, Bill and Ted's Excellent Adventure and the Matrix trilogy, actor Keanu Reeves combines boyish good looks with a Zen-like, almost spiritual calm.
The latter characteristic certainly suits his latest role - that of an alien visitor, Klaatu, who arrives on Earth to warn of an impending global apocalypse.
There is another side to the 44-year-old, however, as journalists at a press conference in London discovered this week.
Though generally good-humoured, his occasionally brusque responses revealed him to be a man who does not suffer fools - or impertinent reporters - gladly.
He was less than impressed, for example, when the moderator of the press conference - who was sitting beside Reeves - accepted a glass of water the actor had intended for the film's director, Scott Derrickson.
Nor did he seem overly pleased when a reporter asked him to prove his environmental credentials by citing the last "green" thing he'd done.
"Hallelujah!" he exclaimed when asked by the BBC News website to comment on the film's use of overt Christian symbolism. "What do you think?"
On other subjects, though, he was more loquacious - among them his pleasure at having erstwhile Monty Python member John Cleese as a co-star.
"Meeting him was fantastic," he said of Cleese, who plays a scientist who tries to convince Klaatu that humanity is worth saving. "He's a lovely, generous man.
"Everyone on set was so excited when he came in. It was great to spend a couple of days with him."
Reeves was also eager to praise Will Smith's 10-year-old son Jaden, who plays a young boy who comes into contact with the extra-terrestrial.
"He's a good kid, very professional," he revealed. "He had a lot of tough scenes that would be a challenge for any actor."
For Reeves himself, the challenge was charting Klaatu's progression from cerebral, emotionless outsider to a more compassionate, sensitive being.
"The story went from him being an alien looking at humanity to him becoming human himself," he explained.
"It's about the decisions and sacrifices he makes on his journey from being separate to becoming whole."
Asked what appealed about the project, the actor said he "thought it would be fun playing an alien".
In addition, though, the film offered the opportunity to comment on current environmental issues and anxieties.
Released during the Cold War, Robert Wise's original film offered a clear allegory for the escalating tensions between the US and the Soviet Union.
"Your choice is simple," warned Michael Rennie's Klaatu at the end of the movie.
"Join us and live in peace, or pursue your present course and face obliteration."
In Derrickson's version, however, the threat to mankind is not a military one but the damage done to the Earth's fragile ecology.
"I liked the idea of telling the same story but updating it to [address] different social issues," said the American filmmaker.
"The earth being at a crisis point, a crossroads - as a story I thought it was a good place to start," agreed Reeves.
"As a species we can be pretty warm and fuzzy," the actor continued when asked what he felt was mankind's saving grace.
It is left to Derrickson, though, to explain why a remake of a 57-year-old film makes sense today.
"I don't think it's a message movie that's telling anyone how to live," he told reporters. "It's more an expression of what I see happening.
"We've made some bad decisions, but people seem to be recognising that and reckoning with it.
"We're trying to figure out what to do about it and what hard choices we have to make to prevent further destructiveness.
"That's a part of human nature that's very admirable, that's worth celebrating and having some optimism about."
The Day the Earth Stood Still is out in the UK on 12 December.