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The six groups in this episode include a cappella group The Bristol Suspensions, pop choir from Liverpool Over the Water, show choir Perfect 6th, all-female country group The Savannahs, Portsmouth University Gospel Choir and musical theatre performers Vocal-i-sing. They must impress the panel of musical judges - Gareth Malone, Kelis and guest judge Seal.

The programme opens with an epic musical mash-up, and the groups then go head to head in a series of knockout choral challenges. First they each perform their show-stopper before battling it out with their opponent in a themed riff-off. The judges then decide which group goes through to the solo battles.

At the end of the programme only two groups remain, and they face the ultimate sing-off. They share the same song, before Seal joins in with the group the judges have chosen to go through.