Leipzig, 1726. Eleven-year-old Stefan Silbermann, a humble organ-maker's son, has just lost his mother. Sent to Leipzig to train as a singer in the St Thomas Church choir, he struggles to stay afloat in a school where the teachers are as casually cruel as the students. Stefan s talent draws the attention of the Cantor Johann Sebastian Bach. Eccentric, obsessive and kind, he rescues Stefan from the miseries of school by bringing him into his home as an apprentice.
Soon Stefan feels that this ferociously clever, chaotic family is his own. But when tragedy strikes, Stefan's period of sanctuary in their household comes to a close. Something is happening, though.
In the depths of his loss, the Cantor is writing a new work: the Saint Matthew Passion, to be performed for the first time on Good Friday. As Stefan watches the work rehearsed, he realises he is witness to the creation of one of the most extraordinary pieces of music that has ever been written.