Gareth Malone is back and this time he wants to get staff in some of Britain's busiest workplaces singing while they work. Travelling across the country, he sets out to create four unique choirs in four very different organisations, which will then sing head-to-head in a contest to find his best workplace choir. Gareth is at Lewisham Healthcare NHS Trust to set up the first of his four choirs from the doctors, nurses and porters at one of London's busiest hospitals. But as the staff come together, the song Gareth chooses for them to sing proves challenging in a way that he wasn't expecting.

In his mission to get some of the country's busiest workplaces singing, Gareth Malone heads west to the Royal Mail in Bristol. He wants to create the second of four choirs that will compete in the contest to find his best workplace choir. As he searches for hidden talent amongst the managers and posties from across the region, the initial reaction from staff is quite mixed. But as the choir begin to bond through rehearsals, Gareth discovers an enormous sense of pride in the workforce and the song he chooses for the choir to sing hits the right note.

Choirmaster Gareth Malone has already set up two of the four workplace choirs that will compete in his singing contest, at Lewisham Hospital in London and at the Royal Mail in Bristol. This time he travels to Manchester to create his third choir amongst baggage handlers, security staff, air traffic control and the fire crew of Manchester Airport. With the staff more used to singing karaoke than choral music, things get off to a bumpy start but, as Gareth begins his search for a soloist, he discovers hidden talent in unexpected places and the choir is soon ready for take off.

Choirmaster Gareth Malone continues his mission to get some of Britain's busiest workplaces singing. This week he travels to the Midlands to set up final choir in one of the country's largest water companies, Severn Trent Water. Once formed, the choir will sing against three other workplace choirs as they compete for the chance to be crowned Gareth's Best Workplace choir. With over five thousand call centre staff and over five hundred workmen, dealing with everything from raw sewage and finding leaks, finding thirty people to make up the choir appears easy. But as staff are struggling to juggle family commitments and busy work schedules, things aren't plain sailing and Gareth begins to feel the pressure.

With all of his workplace choirs set up, the contest to find Gareth Malone's best workplace choir begins in earnest as all four choirs compete against each other for the first time. Each choir is given a new song and Gareth piles on the pressure by announcing that they must create a distinctive performance routine if they want to stand out. Each choir has less than four weeks to prepare, before they must perform in front of the three expert judges at Bristol's prestigious Colston Hall.

After last show's semi-final performances in front of the judges, it is time for the final three to battle it out. They face their biggest challenge yet as they perform in front of an audience of thousands at one of the world's most prestigious choral music festivals - the International Eisteddfod in Llangollen. In the audience will be the three expert judges who will decide which choir will win the overall contest and be crowned Gareth's Best Workplace Choir.