Paddy McGuinness hosts as celebrity investigators Jimmy Carr, Alison Hammond and Amanda Holden try to help brothers Haloo and Zanist from Hertfordshire to spot the fake singers and win £10,000 to treat their mum. With a line-up of imposters including a Cher look-a-like and a magician who keeps alpacas, they may have their work cut out! This week's musical guest is the legendary Lulu, who reveals she would love to duet with Justin Bieber and Bruno Mars.