The Middle Of Things by J. S. Fletcher
A complicated tale of murder, hidden identities, and buried secrets in London's fashionable neighborhood of Bayswater.
Bayswater is a quiet neighborhood whose residents are successful lawyers or medical men, people of independent means, or wealthy colonials returned to their homeland. It is hardly the place to expect a brutal murder and robbery, yet that is exactly what Richard Viner finds himself caught up in when he discovers the body of a neighbor on his nightly stroll, after having spent an evening reading a detective story to his aunt. He protests to his aunt that the events in detective stories never occur in real life. She counters with several mysteries from her own experience. He is still doubtful, but finds she is right when he finds himself in... The Middle of Things.