There has been another Murder in Successville. A priceless piece of art has been stolen from right under DI Sleet's nose, and Bjork is murdered in the process. Sleet and his new sidekick Richard Osman wade into art's black market underworld to catch their culprit. Find the art, and they'll find the killer. This time they investigate Arsene Wenger, an avant-garde art collector whose new gallery is opening at a suspiciously convenient time. Sleet and Osman go undercover as turtle-necked arty types to get some answers. Hilary Clinton is an art teacher and a forger who claims to have gone straight. Richard Osman goes undercover as a student to glean some answers. Zayn Malik is a cat burglar who is a little down and out after being thrown out of his gang. Sleet and Osman break into a creepy paint factory to give Zayn an old-fashioned roughing-up, though Zayn turns the tables when he reveals some shocking truths about Sleet's dad. After coming to terms with his daddy issues, Sleet takes Richard Osman down to Successville's sewers to infiltrate a black market art auction ran by Bill Nighy. Have you kept your eyes and ears open for clues? Could you take out the right person?

This week we're thrown back in time to Victorian Successville, where guest rookie Martin Kemp is tasked with solving the very first Murder in Successville. Local lady of the night Rita Ora has been found slayed in an alley, and DI Sleet and Kemp are tasked with retracing her last steps around the cobbled streets of Successville. They investigate Will-i-am, a science professor who has always got the better of Sleet. Martin Kemp's investigation is disrupted, however, when Will-i-am tricks Sleet into drinking truth serum. Paloma Faith is the landlady of the local brothel where victim Rita worked. Martin Kemp and Sleet go undercover as criminal brothers - the Neville brothers - but there is some confusion as to who is supposed to be the cooler brother. Jonathon Ross is an upper-class gentleman who had no idea that his girlfriend Rita was working at a brothel. Sleet and Kemp go undercover to a gentleman's club where they manage to get invited to dine with Jonathon Ross and his good friend Jamie Oliver. With all three suspects facing execution by the firing squad, Sleet and Martin Kemp have to pick who they think the real murderer is. Have you kept your eyes and ears open for clues? Could you take out the right person?