On the morning of the 30th anniversary of the Glorious Revolution of the Twenty-Fifth of May (and as such the anniversary of the death of John Keel, Vimes' hero and former mentor), Sam Vimes — whose wife is in labour with their first child — is caught in a storm while pursuing Carcer, a notorious criminal who has murdered several watchmen, to the roof of the Unseen University's Library. He awakens to find that he has somehow been sent back in time.
