Graeme and Eirn have no words for what they are to each other. Children, clinging together in a crowded orphanage; friends, battling back to back in a school yard; and bedmates, finally bridging the gap between sleeping next to a body and allowing it to touch you in the night--all of these roles are summed up by just their names: Hammer and Air. The innocent exploration of their newest roles is brutally marred when a violent, ill-tempered master threatens Eirn, and Eirn's "Hammer" kills the man in a fair fight. The two run off into the wide world with only each other for safety. It's difficult to forge a good life with only a blacksmith's hammer and a printer's cleverness, but together, Hammer and Eirn will learn to negotiate the dangers of magic and motion, of sex, obsession, and tenderness, and of the word that can make sense of it all--one word they must earn for themselves.