AVENGERS: INFINITY WAR

★★★ ½ out of 5

Cast: Everyone (Chris Hemsworth, Josh Brolin, Robert Downey Jr., etc.) Director: Anthony Russo, Joe Russo Duration: 2h29m

Count on Robert Downey Jr. as Tony Stark to sum up this two-and-a-half-hour monster Marvel movie in just 13 words: “He’s from space. He came here to steal a necklace from a wizard.”

“He” is an all-powerful bad guy with Josh Brolin’s voice and Washington’s Mount Rushmore chin who gets an even briefer introduction at the end of the opening scene, when news arrives on Earth in the form of what I’m going to call a Hulk-ogram. “Thanos is coming!”

Thanos wants the Infinity Stones, a sextet of MacGuffins that have been noisily coming together for the past 10 years and 18 films. The Time Stone is in a necklace and gives the wizard Doctor Strange (Benedict Cumberbatch) his powers. The Mind Stone sits plainly in the forehead of Vision (Paul Bettany). The Soul Stone is presumably somewhere in Motown. I’ll leave you to discover the others — unless Thanos gets to them first.

Rather than list the rest of the performers, it might be easier to say who’s not in the movie: Paul Rudd’s Ant-Man and Jeremy Renner as Hawkeye sit this one out. The cast is so sprawling that we’re an hour in before we’ve caught up with them all.

One of the very few newcomers is Peter Dinklage in what might be his biggest screen role yet. He plays a giant dwarf who has to help Thor forge a new weapon, after his last one got shattered in Ragnarok. (Hammer time!) His scene is one of a number of (thankfully) lighter moments spread through the picture. Another reminds us of Rocket’s fetish for prosthetic devices.

Christopher Markus and Stephen McFeely are the scribes behind the Captain America movies and return for this one, as do directors Anthony and Joe Russo. They do a remarkably good job of juggling actors and locations that span the Earth, the galaxy … and even Scotland.

And for once a villain’s quest is easy to understand, if not to root for. Thanos has clearly read Malthus’s 1798 Essay on the Principle of Population and decided that the only way to save the universe from ruin is to cut the number of residents in half. “They called me a madman,” he crows at one point, forgetting that “they” are usually right about such things.

So on the one hand we have a being willing to trade trillions of lives for greater prosperity for the survivors, and on the other a group ready to sacrifice their own lives to stop him. And there are sacrifices aplenty along the way — although it must be said that Loki’s back-from-the-dead performance in the last Thor movie makes me wonder if anyone in this universe ever truly perishes.

It’s also worth noting that with so many good guys spread out across so many fronts, there are endless opportunities for herecomes-the-cavalry moments, to the point where one ticked-off character asks why her rescuer was just off-screen for so long before swooping in to help at the last second.

And where previous Marvel outings have delighted in hero-on-hero matchups (Hulk v. Iron Man, Spider-Man v. Captain America, and the amusingly brief Black Widow v. Ant-Man), Infinity War puts all the good guys on the same side — well, except for a short misunderstanding when two teams show up to fight Thanos at the same time. In fact, one of the movie’s most touching moments is a pre-battle chat between, of all beings, Thor and Rocket Raccoon.

The ending is easily Marvel’s most shocking yet, so the less said the better. It doesn’t so much hang viewers from a cliff as drop them off and leave them in the dust below.

It’s a powerful final note, undercut by the understanding that the team is already deep into production on Untitled Avengers Sequel, due out next May.

If Infinity War was the Second World War, I’d go all Churchill and declare that this is not even the beginning of the end. But it is definitely the end of the beginning.

In a quiet corner of the Scotiabank Cinema on Thursday evening, a guy who goes by the name Spider_Inferno was changing into a custom-made Spider-Man costume.

His girlfriend Alyssia Duval, dressed as Thor, was having trouble with the last part — zipping up the back of his mask. Nearby, their friends milled about in Hulk, Iron Man and Captain America get-ups.

The occasion was the early-bird screening of Avengers: Infinity War, the latest in Marvel’s all-star superhero series, which officially opens on Friday.

“I’ve been dressing up as SpiderMan for six or seven years now,” said Spider_Inferno, 35, who appears regularly at conventions, kids’ birthday parties and Comiccon.

“I’ve been a Spider-Man fan since I was five years old. Peter Parker is a real hero, not like Superman, who is the most unrelatable superhero character out there.”

How deep is his love? Spider_ Inferno has a Spider-Man tattoo, his condo is “literally a SpiderMan shrine,” and he is the owner of some 5,000 Spider-Man comics.

“He’s definitely my spirit animal,” he said.

Which made for a good reason to be excited about Avengers: Infinity War, and to dress for the occasion.

“As a huge comic geek, who has read the Infinity Wars comic books, … I’m looking forward to seeing all 10 years of MCU (Marvel Comics Universe) come together,” Spider_Inferno said.

“All those superheroes we love and grew up watching are coming together for an epic story; I can’t wait. I’ve anticipating this for quite a while.”

Standing by in her Thor outfit, Duval, 27, exhibited a more tempered enthusiasm.

“I go to all the conventions with him now, so I dress up, too,” she said. “But I’m a Trekkie; I dress up as Star Trek characters. I love Marvel and the Avengers as well, obviously.”

Steven Lee, 20, was excited to finally be donning even a toneddown version of the wardrobe of his idol Captain America.

“Dressing up as your favourite character — it’s not every day you get to do it,” he said. “I’ve wanted to dress up before, but I didn’t have the right people. Now that we’re all motivated to see this together, the time is right.”

Marjorie, 34, was also new to the costume game.

“Since meeting these people who were dressing up, I thought I might as well join in the fun,” she said.

“It’s like stepping into another universe, having fun, letting go, letting your nerd flag fly.”

The provider of the super apparel — with the exception of Spider_Inferno’s, of course — was Karine, aka Iron Man, 44, whose home is “full of cinema stuff.”

Originally from Venezuela, she grew up reading DC Comics, but has since converted to Marvel. She was approaching the evening’s main event with an open mind.

“I always avoid trailers,” she said. “I really want the element of surprise.”

As Spider_Inferno indulged other filmgoers’ selfie requests, a young woman in an Iron Man hoodie, and matching mask under her arm, gave a bashful wave to the costumed crew.

“Dressing up — I just like,” said Carol-Ann Teasdale, 21, who had come to the screening on her own.

“I don’t know how to describe it. It helps me connect with other people at the cinema.”