Moon Song is a love and ghost story. Journalist and musician, Isoldé Labeale, flees a London that, after "nine-eleven", is becoming as oppressive as the Belfast of the Troubles in which she grew up. She goes to the West Country to work with an old lover and meets the international concert organist, Mark King. They fall in love. Isoldé goes to live with him at his Cornish home, Caergollo, and discovers that Mark is the adopted brother of her hero, the late Celtic folk singer Tristan Talorc, now dead. She meets the Woodfolk of Nectan's Kieve who tell her Tristan died too soon, without finishing his last song. The Woodfolk need the song and ask Isoldé to find it. The search brings conflicts between her and Mark