The Adventures of Philip Marlowe was a radio show based on Raymond Chandler's private detective character, Philip Marlowe. Unlike many other detective dramas during that time, this show had a distinct hardboiled tone and featured few quips or quaint characters. The show's format/style followed Marlowe as he solved crimes using his keen observational skills and deductive reasoning, while encountering a variety of intriguing characters along the way, showcasing Marlowe's strong sense of justice and his grittier, urban environment.

The show first aired on June 17, 1947, on NBC, under the title The New Adventures of Philip Marlowe, with Van Heflin playing the lead role. The NBC series ended on September 9, 1947. In 1948, the series moved to CBS, where it was called The Adventures of Philip Marlowe and starred Gerald Mohr. By 1949, the show had become the most popular radio show in the United States. The CBS version had a run of 114 episodes from September 1948 to September 1950, with an additional summer run of episodes airing from July 7 to September 15, 1951.

Sources: archive.org, wikipedia.org, otrcat.com