The latest bid to fill the looming gap left by the end of ‘Harry Potter’ is this scattershot but entertaining adaptation of ‘The Saga of Darren Shan’, a series of kids’ books narrated by the central character, a teenager caught up in a supernatural war. John C Reilly gamely chomps the scenery as showman Crepsley, who invites Darren (Chris Massoglia) into an underworld of freaks and vampires. There’s a lot of backstory and the plot is often hazy. There are also so many characters that some barely register, while others – like our teen hero – are just unlikeable. It’s very energetic, but a more relaxed sequel, in which everyone has fun, might be a big improvement.