[2] The novel is set during the period of the Napoleonic Wars[3] and follows the adventures of Anthony Lammas, a young professor at St Andrews, who is drawn into a plot to kill the prime minister Spencer Perceval.

Anthony ("Nanty") Lammas, a young professor at St Andrews, is sent by his college to London to plead for funds from Lord Snowdoun, Secretary of State for Scotland.

Having grown up among the fishermen of Fife, Nanty is a member of The Free Fishers, a secret mutual aid organisation which has been tasked by His Majesty with tackling Mrs Cranmer's treasonous spying activities.

On the road they meet Duncan Dott, a town clerk who is coincidentally seeking an interview with Mrs Cranmer to get her signature in connection with a minor legal matter.

She confides that her husband's treasonous activities are coming to a head: he is plotting to murder her cousin, the prime minister Spencer Perceval, and to pin the blame on her.

An injured Harry escapes to a nearby manse where he meets Nanty and his group, and also Sir Turnour who has been searching for him to force the duel.

The house is almost empty, but in a back room they find Duncan Dott, locked in after being too persistent in demanding an interview with Mrs Cranmer.