Martin watches a Sherlock Holmes film at the cinema and is inspired to kill Mrs Barrows. As he is a non-smoker and a non-drinker, he decides he can mislead any future investigation by smoking and drinking at the scene of the planned crime. He buys a half-bottle of whisky and a packet of cigarettes. However, in her flat, after a series of botched attempts, his conscience gets the better of him and he cannot kill her. He tries to remove all evidence when MacPherson appears suddenly, and manages to avoid detection. Back in the office, MacPherson interrogates Martin and finds his denial more plausible than Mrs Barrows' claims. She cannot take any more, accusing them all of being mad, and she leaves for good. Thus, Mr Martin wins his "battle of the sexes".