When Keanu Reeves was filming Speed, in 1993, he spent every spare minute learning lines in his trailer. These lines weren’t from the film he was working on – as Jack Traven, the SWAT officer who takes control of a bomb-laden bus, Reeves didn’t have a great deal to say – but from William Shakespeare’s Hamlet, a well-thumbed copy of which he would carry around on set.

His day job was zooming through Los Angeles with a flustered Sandra Bullock and a coachload of screaming extras. Monologuing as the tragic Prince of Denmark, on the other hand, was me-time.

“I finished playing Jack, went into the trailer, and, you know – 'How all occasions do inform against me,/ And spur my dull revenge’,” he says, reeling off the opening few lines of Hamlet’s last soliloquy. Did it help him cope with what was, at that point, his most commercially prominent role to date? “Hum.” He pauses. “I don’t know. There was definitely a yin and yang thing going on.”

As he continues, what soon becomes clear is that those snatched moments of Shakespeare helped Reeves make sense not so much of Traven or Hamlet, but of himself. He was 29 years old at the time, with a career that was skyrocketing. But Reeves didn’t see himself as an action hero – or not just an action hero, at least.

Speed was a hit, and Reeves with it. The director, Jan de Bont, had worked as cinematographer on Die Hard, and both films offered a new, pared-down, conceptually clean kind of action cinema after the muscle-bound excesses of the previous decade. “He’s an action hero for the Nineties,” De Bont said of Reeves, and back then, the line sounded like a compliment.

Out of control: Keanu Reeves and Sandra Bullock in 'Speed' Credit: MGM/Everett/REX/MGM/Everett/REX

More of the same followed. Chain Reaction in 1996 was, he says, “a great but tough experience”, largely because the script he signed on for “wasn’t the script that showed up”. It made him cautious, and later that year, when Twentieth Century Fox came calling to enlist him for a Speed sequel, he made other plans.

“When I was offered Speed 2, Jan came to Chicago and so did Sandra, and they said, 'You’ve got to do this’,” he recalls. “And I said, 'I read the script and I can’t. It’s called 'Speed’, and it’s on a cruise ship’.”

When he was next in Los Angeles, William Mechanic, the then-head of Fox Filmed Entertainment, tried to persuade him with a $12m pay cheque. “And I told him, 'If I do this film, I will not come back up. You guys will send me to the bottom of the ocean and I will not make it back up again. I really felt like I was fighting for my life.”

So Reeves turned down Speed 2, and also the role of Chris Shiherlis in Michael Mann’s Heat, which eventually went to Val Kilmer. Instead, he took off to Winnipeg, Canada, for a season at the Manitoba Theatre Centre. The role he played, of course, was Hamlet.

As a result, Reeves was effectively blacklisted by Fox for more than a decade, only working with the studio again in the 2008 remake of The Day the Earth Stood Still, which was hardly worth the wait.

So would Reeves make the same decision again, in the full knowledge of how things would pan out? “Yeah. Y-ee-aa-h,” he says, before rumbling with laughter.

“That’s a good old Hollywood story! That was a whole, 'Hey, kid, this is what happens in Hollywood: I said no to the number two and I never worked with the studio again!’” He waggles his right hand, an invisible cigar clamped between his knuckles.

Reeves doesn’t have the air of a grizzled veteran, but at the age of 50, and with 56 feature-film credits to his name, he counts as one. He’s in the UK to talk about his 57th: a revenge thriller called John Wick, in which he plays a former freelance assassin who reluctantly comes out of retirement for one final bloodletting spree.

Keanu Reeves in 'John Wick' Credit: Everett Collection/REX/Courtesy Everett Collection/REX

It sounds like the kind of B-movie wheeze Liam Neeson might have dashed off between Takens. In fact, it’s one of the best straight action films North America has produced in the past 10 years, and Reeves’s own best film in at least as long. When we meet in a London hotel – him looking exactly as you’d expect, in a black suit and shirt, with hair slicked back and mossy beard neatly clipped – he’s grinning like he knows it.

John Wick suits the Beirut-born, half Chinese-Hawaiian, half-English actor. It’s fusion cinema. The setting is present-day New York City, spattered in streetlit, Sidney Lumet grit, but its style is pure Seventies Hong Kong, with surgically steady-handed camerawork, a ripened sense of mischief, and the kind of limber, elegant combat that brings to mind names like Kelly and Astaire rather than Stallone and Schwarzenegger.

The directors, Chad Stahelski and David Leitch, are martial artists and fight choreographers: Stahelski worked as Reeves’s stunt double on Point Break and The Matrix. The moment Reeves read the John Wick script, he sent it to the pair, who he knew were looking for something to direct: “And luckily, they responded to the material,” he says.

What was in it for Reeves is slightly more complicated. It’s a big, blazing-charisma, movie-star role. But what drew him to the character, he says, was his sadness. At the start of the film, John Wick’s wife passes away from some unspecified disease; the day after, a cute puppy turns up on his doorstep. It’s her parting gift to her husband: something to remind him how to love in the grey days ahead.

This is all played disarmingly straight, and Reeves, whose characters are often men who have battened down their souls against life’s storms, is like a human breakwater, hammered by grief. But then a swaggering young Russian gangster (Alfie Allen) steals John Wick’s meticulously restored 1969 Ford Mustang, and also kills his dog in the process. But this – unlike his wife’s death – is a fate John can push back against. So down he goes to the cellar, and out come the guns, knives, grenades, and the rest.

“For me, it was John’s grief that made it personal,” says Reeves. “It was strong enough to make him want to unearth his past. I thought of it not as revenge but as reclaiming.”

The impulse is understandable. Reeves’s own past, both recent and distant, has been fraught with grief. His father Samuel abandoned him and his mother when he was three years old: Reeves last saw him in Hawaii when he was 13.

In 1993, he lost his close friend, the actor River Phoenix, to a drug addiction he had developed during the making of My Own Private Idaho. The two young actors had met the previous year while filming I Love You to Death and Reeves had personally persuaded Phoenix to take this role, driving over 1,000 miles from Toronto to Florida by motorcycle in December 1989, the once-in-a-lifetime script by Gus Van Sant burning a hole in his back pocket. In 1999, as The Matrix pushed his star status further heavenwards, he and his girlfriend Jennifer Syme lost their daughter in the final stages of pregnancy; 18 months after that, Syme was killed in a car accident.

Reeves is reluctant to talk about any of this, or in fact anything pertaining to his personal life. When I suggest his eclectic career could be linked to his unsettled childhood (he mostly grew up in Toronto, but moved around frequently as his costume-designer mother looked for work) he demurs, offering “a little bit”, before approaching the subject from another, more comfortable angle. He’s much happier talking about what he gleaned from movies during this time, which was a sense of empowerment.

“There was a television channel in Toronto that would play kung fu movies every Sunday afternoon,” he remembers. “And I don’t know if it’s wish-fulfilment, but what those actors were capable of doing with their bodies struck a chord.” He was spellbound by the fight scenes and perfected the twangy, cod-American accent of the dubbed English dialogue. But his affinity ran deeper than that. “The fights were fun, and they looked cool, but there was magic in them too. The flying, the costumes, the defined sense of right and wrong. The characters could be capable and heroic, and I was fascinated by that.”

That fascination shone through most obviously in his directorial debut in 2013, a fun and authentic kung fu movie called Man of Tai Chi, which he can’t talk about without throwing in a menacing cackle. (As well as directing, he played the bad guy.)

Keanu Reeves and Hugo Weaving in 'The Matrix Revolutions' Credit: Warner Bros Pictures

But perhaps it’s also why he feels obliged to train so hard for his more physically demanding roles. For The Matrix, he undertook four months of martial arts and stunt work before the cameras rolled; on John Wick it was another three. Stahelski and Leitch knew what Reeves could do, because in the late Nineties, they had taught him to do it.

“They wanted even more from me than they got,” he says. “But the stuff they wanted me to do I couldn’t do. Because I was just, like, exhausted. And I felt like I let them down.”

You’re 50 years old, though, I say. Couldn’t you have just used a stunt double? “Arahargh! Umm, no. I want to be there. That’s what carries the audience along.” So he’s determined to keep doing his own stunts? “If I’m there, it’s not a stunt.”

For a boy growing up in Toronto, the closest thing to appearing in your own kung fu movie was ice hockey, and for a while, Reeves toyed with the idea of going pro. But when he was 14 years old, he played Mercutio in a community centre production of Romeo and Juliet: the role got him an agent, who secured a steady stream of television work, which in turn led him to film.

His fourth feature, River’s Edge, in 1987, was the one that marked him out as a serious talent, but it was Bill & Ted’s Excellent Adventure, two years later, that revealed him as a star. He followed it with Point Break, My Own Private Idaho and the Bill & Ted sequel. Few actors have the range to carry three films as diverse as those over a lifetime. Reeves polished them off in a single year: 1991.

Fifteen days after he’d been frolicking in the waves with Lori Petty in Kathryn Bigelow’s surfer-bank-heist thriller, he was gliding down an escalator at Portland airport, towards River Phoenix and Gus Van Sant and what Reeves now calls “our Shakespearean street-hustle movie”.

Keanu Reeves and River Phoenix in 'My Own Private Idaho' Credit: Moviestore Collection/REX/Moviestore Collection/REX

My Own Private Idaho drew inspiration from Shakespeare’s Henry IV plays, John Rechy’s novel City of Night and the real-life experiences of one of Van Sant’s friends, who had been a street kid and a hustler in the American Midwest. Reeves’s character, Scott Favor, is the son of Portland’s mayor, and is artfully slumming it while he waits to come into his inheritance. But for Phoenix’s character, Mike Waters, the struggle is real. He is also in love with Scott, and tells him so as they sit together by a campfire.

“I only have sex with a guy for money,” says Scott, from the edge of the fire’s flicker and glow. “I could love someone if I, you know, wasn’t paid for it,” Mike nervously replies. “And I love you, and you don’t pay me.” Reeves and Phoenix rewrote the scene together on set, two friends working together as the light faded. It’s the single best thing Reeves has ever done; may ever do.

It was certainly a change of speed for an actor whose recent work on Bill & Ted had led to a spin-off cartoon series and breakfast cereal. But Reeves enjoyed the change of pace, just like he always has. “I needed a real experience, and sometimes you have to slow down,” he says. “But it’s also cool to burn bright, man. It’s very fun.”

John Wick is released on April 10