Hannay has a long series of reactions when he finds the dead body of Scudder on his apartment floor. First, he feels a sense of horror. He has to cover the corpse with a tablecloth and drink some brandy before he can think straight. He notes that he has killed men before in battle but is not used to witnessing coldblooded murder.
As his wits return, Hannay carefully searches to make sure the killer is not hiding anywhere in the apartment. Then, he begins to think about his predicament. He realizes that he has scarcely returned to England and is likely to be considered the murderer if he goes to the police, especially as Scudder's fantastic story about an international Jewish conspiracy to start a war so that capitalists can rake in the money is too outlandish to be believed. However, he now believes the story. It then dawns on him that whoever killed Scudder will next target him.
Hannay decides his best alternative is to flee and lie low while he looks for more evidence to support Scudder's claims. He realizes both the group that killed Scudder and the police will be after him, the first to murder him and the second to arrest him for murder. He will have to be nimble. However, oddly enough, the tasks before him give him energy and "comfort." He has a cause again and decides,
if my neck’s safety was to hang on my own wits I was prepared to be cheerful about it.