The final film in the Marvel Cinematic Universe's Infinity Saga has its work cut out. Not only does it need to bring a 22 film, 11-year series to a satisfying climax and seed the MCU's remixed continuation, it also has to resolve that cliffhanger – half of creation reduced to dust by Josh Brolin's cosmic meanie Thanos, in 2018's Infinity War – ideally, without cheating. And, true to franchise form, keep those raccoon-based gags lively.

Even if directors Anthony and Joe Russo veer close to overkill eventually, their whip-smart navigation of high-stakes set-pieces, surprises, quips and cameos must be chalked up as a super-sized success. Cannily, they take their time initially. The immediate effects of Thanos's victory sting as the surviving Avengers slump into despair. Five years later, even Black Widow's (Scarlett Johansson) sarnie looks depressed. The situation seems hopeless, until Ant-Man (Paul Rudd) kicks the quip-driven action into new realms for a getting-the-gang-back-together-style heist movie with a quantum twist or ten.

To explain more would be spoiler-y and pointless; the 'space magic' logic makes little sense. But writers Christopher Markus and Stephen McFeely's comic asides work as sleight-of-hand, directing us towards character-based developments for a gloriously entertaining mid-section. Although it verges on fan-service and self-service, the film's central hour earns both because the balance of comedy, drama and action to playful invention and careful characterisation holds so sure.

An under-deployed Johansson aside, every player is newly stretched: Chris Hemsworth extends his evolution into the MCU's comic dynamo as Thor; Robert Downey Jr delivers a more-human-than-ever Iron Man; Mark Ruffalo adds shades to the Hulk; and Chris Evans maximises Captain America's nobility (and he's had a shave). Even if the Lord of the Rings-gone-ballistic climax overdoes the CGI, these characters are never compromised. Best of all, Endgame bucks Marvel's emphasis on soap-opera serialisation by granting some arcs a bold, even poignant sense of closure. When the climax drops, it won't just be dust in MCU-watchers' eyes.

General release from Thu 25 Apr.