London at the dawn of 1918 and Ireland's most famous literary figure, WB Yeats, is immersed in supernatural investigations at his Bloomsbury rooms.

Haunted by the restless spirit of an Irish girl whose body is mysteriously washed ashore in a coffin, Yeats undertakes a perilous journey back to Ireland with his apprentice ghost-catcher Charles Adams to piece together the killer's identity.

Surrounded by spies, occultists and Irish rebels, the two are led on a gripping journey along Ireland's wild Atlantic coast, through the ruins of its abandoned estates, and into its darkest, most haunted corners. Falling under the spell of dark forces, Yeats and his novice ghost-catcher come dangerously close to crossing the invisible line that divides the living from the dead.