Gareth has taken on the ambitious task of working with eight raw but talented individuals who've never tackled anything quite like Handel's monumental Messiah. Thrown in at the deep end, each intricate chorus of the hundreds-of-pages-long score presents a fresh challenge for his novice group. So far, their journey has been within their small group of eight. However, they're on the verge of a significant step: soon, they'll be singing alongside the professionals – the BBC National Orchestra of Wales and Chorus of Wales.

At the beginning of this episode, the pressure is already building. While the group tries a brief escape to the coast outside Cardiff, to Penarth Pier, rehearsals continue, but one member is noticeably absent. Foo Seng is feeling the weight of expectation and the complexity of the music. As Gareth's belief in his singers grows, he offers one of them, Rosie, the opportunity to perform a solo piece.

Gareth is continuing a long and significant tradition: using Handel's Messiah to raise money for good causes, this time for BBC Children in Need. He explores this history with a visit to the Foundling Hospital, the very place where it all began 275 years ago, and where librarian Catherine Hogg offers him insight into Handel's lasting impact. Just hours before the performance, the dress rehearsal at Llandaff Cathedral takes a dramatic turn. During the powerful "Thou Shalt Break Them" section of Messiah, something unexpected happens to one of the singers and doctors are called to the scene.