An illustrated short story from the queen of crime. Poirot is summoned urgently by special messenger late at night to 'Sharples', the home of Lord Alloway, head of the Ministry of Defence and a potential future Prime Minister. Travelling there with Hastings, he is introduced by their host to Admiral Sir Harry Weardale, the First Sea Lord who is a guest at Sharples together with his wife and son, Leonard. The reason for the summons is that the secret plans for the new 'Z'-type of submarine were stolen some three hours earlier.