Berkeley's work stood out for its focus on the psychology behind crime, often highlighting moral ambiguity and unreliable narratives. Unlike traditional mysteries where the detective solves the case through logic, Berkeley was more interested in exploring multiple possibilities, false leads, and the role of human error in investigations.

Roger Sheringham series: Berkeley's most famous character, Roger Sheringham, is an amateur detective who appears in several of his novels, including The Poisoned Chocolates Case (1929). Sheringham is often portrayed as flawed and arrogant, contrasting with the infallible detectives seen in many Golden Age mysteries.

Francis Iles novels: Under the pseudonym Francis Iles, Berkeley wrote psychologically driven novels such as Malice Aforethought (1931) and Before the Fact (1932). These works are early examples of "inverted detective stories," where the criminal's identity is known from the beginning, and the suspense comes from whether they'll be caught.

Malice Aforethought is particularly famous for its darkly comic portrayal of a murderer planning to kill his wife, showing Berkeley's mastery of psychological tension.

Before the Fact became even more famous after being adapted into the 1941 Hitchcock film Suspicion.

Berkeley was a founding member of the Detection Club, a group of British mystery writers that included luminaries like Agatha Christie and Dorothy L. Sayers. The club was known for its rules on fair play in detective fiction-ensuring that readers had all the clues necessary to solve the mystery along with the detective.

Berkeley's influence on the detective genre lies in his willingness to subvert its conventions. He moved away from the purely puzzle-driven approach of many of his contemporaries, instead focusing on character psychology and the ambiguity of moral choices. His "inverted" mysteries, where the reader knows the identity of the killer from the start, were groundbreaking at the time.