Two stars

There's a scene about a third of the way into this movie where Harley Quinn (Margot Robbie) and her new young accomplice, pickpocket Cassandra Cain (Ella Jay Basco) watch television as they hide out in Harley's small apartment.

On their small screen is an episode of Tom & Jerry, all bright colours and mad violence as cat and mouse try to destroy each other in ridiculous ways. The reference is clearly deliberate, and you will find Birds of Prey an excessive, frazzled tale of hyper-violence that plays out like Tom & Jerry in the colourful and hazardous world of Gotham City.

With thinly drawn characters and a relentless narrative that's over-explained and over the top, you won't need caffeine for a week.

Produced by Robbie, she takes the lead with the story playing out chronologically after the conclusion of Suicide Squad (2016).

In an animated opening sequence, we learn Harley's entire back story: a sad tale of childhood neglect as she is shuffled from bad father to bad nuns, and from there to bad company. She gets a PhD, becomes a psychiatrist, meets the Joker in prison and falls in love.

But now, sadly, she's been dumped. We pick up the story as Harley is out on the streets and looking for solace or forgetting with the help of the bottle. In a bling-filled nightclub she runs into Roman Sionis (Ewan McGregor), a particularly nasty gangster who is trying to get his hands on the fortune of a mafia family, the key to which is a large diamond now in the hands of the young Cassandra.

As Harley joins the hunt for the girl, she finds that others are on her tail.

There's Gotham City police detective Renee Montoya (Rosie Perez), and the daughter of the mafia family in question, Helena Bertinelli (Mary Elizabeth Winstead) who is armed with a cross bow. Then there's Black Canary (Jurnee Smollett-Bell) a singer in Sionis' nightclub who he recruits as his driver. She has some nifty martial arts moves and a deadly scream.

The story is jumble of motives and shifting allegiances, and a mad dash to the bottom of the DC Extended barrel, with the warring factions increasingly drawn up along gender lines.

Harley Quinn's attempts at emancipation seem self-destructive, vindictive, playfully sadistic but ultimately mostly forgotten as the plot drives on, beat by beat, blow by blow.

At one point she apologises to Cassandra for her flaky behaviour: "Sorry," she says, "I'm just a terrible person."

With redemption therefore not an option, Director Cathy Yan is really just concerned with the frenetic energy of the piece, and whilst there are some superbly choreographed fight scenes, there's nothing here for any of the actors to make more than cartoons of their characters.

You can clearly see Ewan McGregor struggling at times.

Only Smollett-Bell seems to find some nuance in her character: a slow smouldering resentment that lies beneath, where everything else in the movie is sliced, diced and presented brightly on the surface.

Stylised violence and antisocial delinquency can be rendered with great skill on screen: think Kill Bill (2003) or A Clockwork Orange (1971).

Writer Christina Hodson makes Birds of Prey a babbling, post-modern nightmare, and whilst Robbie is highly watchable, her unrelenting voice over and the sheer kaleidoscope of the storytelling makes you want to scream for fresh air.