When two YouTubers uncover a mysterious grave in an abandoned churchyard, what starts as harmless entertainment soon turns darker when their discovery begins to unwrap a mystery which has lain dormant for over a century.

Birdsong tells a mesmerising story of love and courage, before and during the war. In pre-war France, a young Englishman, Stephen Wraysford, embarks on a passionate and dangerous affair with the beautiful Isabelle Azaire that turns their worlds upside down. As the war breaks out, Stephen must lead his men through the carnage of the Battle of the Somme and through the sprawling tunnels that lie deep underground beneath the battle fields. Faced with the unprecedented horror of the war, Stephen clings to the memory of Isabelle and the idyll of his former life as his world explodes around him.