Brad Bird‘s first film outside Pixar since The Iron Giant, now teaming up with Skydance Animation, was always going to be hotly anticipated. Add to that the fact that he has reportedly been planning Ray Gunn for the past 30 years, and you have the recipe for an all-time classic. That’s the theory, at least.

It certainly feels like a passion project, for better and worse. The imagination on display is phenomenal: the concept, the world-building, the retro-futurist aesthetic. Everything feels vibrant and meticulously realised, as though it has been transplanted directly from Bird’s brain. The problem is the story itself. Reminding me of Edgar Wright’s Baby Driver, another idea conceived in its director’s youth, where the finished product sometimes feels as though a teenager wrote it. The issue with making something thought up so long ago is the storyline can inevitably feel a little simplistic.

Sam Rockwell voices the titular Ray Gunn, a private detective in a retro-futurist metropolis investigating a conspiracy involving pop sensation Venus Nova (Scarlett Johansson), a temperamental diva whose spectacular outbursts who divorces husbands quicker than she can release an album. Along the way, he navigates seedy nightclubs, malfunctioning ray-guns, and a colourful criminal underworld, with a murder conspiracy at its centre. Inspired in part by The B-52s song “Planet Claire”, Bird’s vision combines 1950s detective fiction with science fiction. It’s a wonderful setting, even if the plot seldom matches its creativity.

The plot has more in common with Devil in a Blue Dress, for reasons that become clear early on, but it’s the set-pieces that linger in the memory. There’s a phenomenally animated chase, a faulty gun that takes the film on an unexpectedly David Cronenberg-esque detour, a fun confrontation in an elevator, and a moment involving a henchman’s compulsive flicking of his lighter that feels lifted from the opening of Temple of Doom. These sequences have an energy and inventiveness. The problem with the story is that it’s predictable – the “twist” about concealed identities arrives far too late considering how obvious it is, and the final reveal is formulaic, taking a page from the Disney model of the secret villain being the most obvious candidate.

Where the film succeeds is in the ancillary characters, the set-pieces, and the details that bring the world to life. The noir references are delightful, with Matt Berry voicing Francis Xavier, a slug clearly modelled on Sidney Greenstreet, alongside his trigger-happy henchman Gunsol, who owes something to both Peter Lorre and Elisha Cook Jr in The Maltese Falcon. On a separate note, I’d like to celebrate that this is the second film to feature an animated Lorre this year. I am all for it. Even better is Tom Waits as Eye-Ra, Ray’s alien operative, derisively referred to as “The Tripod” due to his three-pointed legs and his single, photographic eye. He’s the closest thing to a genuine film noir character in the film, and all that’s missing is a cigarette dangling from his lips, but I’m guessing that was a no-no. The scenes of Eye-Ra scrambling over rooftops, clinging onto moving vehicles, are among the most breathtakingly animated in the film, and the scene where he is confronted by the killer feels suspenseful in a way that feels completely different to the rest of the film. It is telling though, that the breakout character of the film is the least conventionally human.

More damaging than the rote story though, is the character animation. Rockwell’s vocal performance is excellent, yet the character design makes him frustratingly inexpressive. It’s a problem when your lead animated character isn’t particularly animated. I couldn’t help wondering whether Eye-Ra was originally intended to be the protagonist, with his hangdog expression, trenchcoat, and world-weary outlook, but maybe the studio mandated a slicker, more conventional hero.

Less Blade Runner than Duck Dodgers, Ray Gunn is still a qualified success. There are issues with the narrative that could be credited to the gestation period of this creation. The plot may be simple, the twists predictable, and some of character design is basic – especially the human characters, but there is no denying the visual creativity that fills every frame. It’ll probably not go down as an instant classic on the scale of The Incredibles, Ratatouille or The Iron Giant, but the world Bird has constructed is so rich in detail, atmosphere and bizarre flourishes that it’s a pleasure to just spend time in – even if every once in a while, you’re reminded of the plot.

Ray Gunn is in UK cinemas from 8th December