Avengers Assemble, Joss Whedon, 142 mins (12A) Albert Nobbs, Rodrigo Garcia, 113 mins (15)

In case you ever wondered what Scarlett Johansson was doing in Iron Man 2, or why Jeremy Renner popped up in Thor, or why Samuel L Jackson had a cameo in Captain America, here's your answer.

For years, Marvel has been laying the groundwork for a blockbuster which would bring together several of its most famous superheroes, and now it's arrived: Avengers Assemble features Iron Man (Robert Downey Jr), Thor (Chris Hemsworth), Captain America (Chris Evans), and the Hulk (Mark Ruffalo). Also on board are two assassins, the Black Widow (Johansson) and Hawkeye (Renner), while Jackson is back as Nick Fury, the head of their secret organisation, Shield.

In the movie, it's Jackson who gets the superheroes to join hands for the gamma-irradiated equivalent of an all-star singalong at the end of a charity concert, but in reality the man with this job is Joss Whedon, the creator of Buffy the Vampire Slayer, and the co-writer of one of this year's most entertaining films, Cabin in the Woods. I can't imagine a better choice. Whedon is a past master at co-ordinating numerous characters, and he makes sure the Avengers all have their moment in the sun, as well as a sizeable portion of his trademark screwball dialogue. In scene after scene, someone thinks they've had the last word, only for someone else to top them. Even the Hulk is funny, and he gets precisely two words.

But as snappy as his film is, Whedon can't quite make Avengers Assemble seem anything more than a marketing novelty, principally because he hasn't come up with a story that's big enough to squeeze in this many larger-than-life characters. The plot of Avengers Assemble is as follows: there are some superheroes called the Avengers, and they assemble. They do most of their assembling on board Shield's flying headquarters, while the film's baddie (Tom Hiddleston as Loki, last seen in Thor) is safely in custody, which means that, even with a two-and-a-half-hour running time, Avengers Assemble doesn't have the colossal scale it needs. Why unite Earth's Mightiest Heroes, as they call themselves, only to have them chatting in a succession of grey boardrooms and corridors? And why make those corridors even murkier with post-production 3D?

It's not until the grand finale that the Avengers properly get to strut their superpowered stuff. And even then, their opponents are a swarm of indistinguishable, digitally rendered alien goblins whose idea of invading the planet is to buzz aimlessly round and round New York. It's common knowledge that a hero is only as interesting as the villain he or she is up against, so when the sequel comes along – and it will – the Avengers should pick on someone their own size.

Another film about people in costumes with dual identities, Albert Nobbs snagged Oscar nominations for two of its actresses, Glenn Close and Janet McTeer, both of whom spend the film in drag. Close, who first performed the role off-Broadway 30 years ago, stars as a woman who's been living as a man for her entire adult life, while working in a Dublin hotel at the end of the 19th century. The film's immediate problem is that her disguise isn't very good. It's not just that Close doesn't look like a man, it's that she doesn't look like a human being: her coating of prosthetic make-up is so smooth and waxy that, with her stiff stance and her outsized bowler hat, she could be the Butler-bot 3000. Close is also too old for the role. When she starts courting Mia Masikowska's opportunistic chambermaid, her cross-dressing seems less of an issue than the four-decade age gap.

For all that, Albert Nobbs is a sweet, tender tragicomedy, and Close is so winning that you soon stop worrying about her androgynous android appearance. She plays Albert as a timid, vulnerable innocent who gets a belated glimpse of a wider world: she's the aunt (or uncle) of Chaplin's little tramp.

Critic's choice

The life and times of a reggae legend are revealed in Marley, the new documentary from Kevin Macdonald. Love, sex and self-deception are the themes of Beauty, a hard-hitting gay-themed drama from South Africa with an unnerving lead by Deon Lotz. Austrian director Karl Markovics makes a powerful debut with Breathing, about a teenager let out of jail and starting a new life.