It is the semi-final of Gareth Malone's contest to find Britain's most entertaining, undiscovered amateur choir. The four groups Gareth has handpicked from across the country are being brought together for the first time at bootcamp, before they go head to head to stay in the contest. They face intensive mentoring from Gareth and some of the UK's top vocal and performance coaches as part of a challenge designed to target and overcome their musical weaknesses. Emotions and tensions run high as two choirs grapple with picking the perfect soloist, while another must tackle their lack of self-belief. It is a race against the clock to perfect their semi-final performances before the groups sing live in front of an invited audience and a jury of musical experts. The jury's votes decide which groups will go through to the grand final and which choir will leave the contest for good.