John Milton is sent to Italy to investigate the death of a colleague from Group 15, the secret assassination squad that liquidates those considered to be impediments to the furtherance of British interests. Milton discovers that the agent was involved with the Camorra, the powerful Mafia clan that controls the territory from Naples to the tip of the Italian boot. He identifies the assassin as a man nicknamed Tarantula.

Now Tarantula, and his boss, are entries in Milton's ledger.

And all debts need to be paid.