In this second outing, the superheroes deal with Iron Man Robert Downey Jr’s rogue robot.

With so many characters jostling for attention and so many sequel-friendly storylines left dangling, this fantasy may prove puzzling for all but the most committed comic-book fans.

You certainly need your wits about you to cope with the plot, which finds wisecracking Iron Man inadvertently creating a rogue peacekeeping robot (voiced with enjoyably sly disdain by James Spader) whose aim is to destroy rather than preserve humanity.

As the Avengers rush about the globe to save the day, the ensuing battles have all the CGI-boosted heft a megabudget can buy. But, in the end, there are only so many superhero smackdowns a body can take and the film’s best moments arise from the tenderly romantic rapport between Scarlett Johansson’s Black Widow and Mark Ruffalo’s Hulk.