Martinmas is the fourth instalment of 1588: A Calendar of Crime, a collection of short stories published in step with the sixteenth century calendar.

In St Salvator's college at the start of the academic year a young student claims that he has seen the ghost of a Spanish soldier. Giles and Hew dismiss this as the fevered product of a wild imagination; the students are unsettled by a spate of violent storms, and fears of the apocalypse readily resurge. In the close confines of college, they can be contained. But when a merchant dies, on the feast of St Martin known as 'killing time', with the words 'dead Spaniard' the last upon his lips, the terror of the students spills out to the streets, and Hew is called upon to rid the town of ghosts.