 After following a man with an Italian tattoo to an interned Italian ship, the Olterra, he discovers that the ships hold is being used as a workshop and base for the operations with an underwater door being used for the manned torpedo's and frogmen, which leaves them undiscovered by Spanish authorities.Crabb reports the discovery of the Olterra to his superiors but under the laws of neutrality, he cannot arrange an attack without top level authority.Meanwhile, the Italians plan a major attack on a British convoy.