Dredd director Pete Travis returns to the festival with City of Tiny Lights, a noir-ish modern day gumshoe flick that makes the most out of a charismatic leading performance from the perpetually underrated Riz Ahmed.

Set on the gloomy, rainy streets of London, it’s the story of Tommy (Ahmed, in his fifth film to play the festival in the past several years), a private eye who takes a missing persons case brought to him by a kindly prostitute trying to figure out the whereabouts of her best friend. Tommy’s investigation into her last known whereabouts turns up a dead body and a lot more questions, ones that will take him into the worlds of religious extremists, drug runners, and property developers. It also drums up memories of an incident from his teenage years that he would like to forget.

City of Tiny Lights doesn’t offer much of anything new in the plot department. It’s a rather boilerplate sort of thriller, but Travis keeps things moving briskly despite a slightly repetitive script that spins its wheels at a few points. It moves with a sense of urgency and purpose, and Travis gives as much dramatic weight to flashbacks to Tommy’s childhood as he does to the increasingly complex and dangerous case at hand.

But the film belongs to Ahmed, whose wide eyes belie a cunning intelligence. He’s not a detective that needs to swagger because he already has a lot of respect within his community. He’s delicate and sensitive, but not fragile and easily broken. Following him around is a joy.