Howard Duff made the role of Sam Spade his own, bringing the San Francisco shamus to radio life from 1946 until 1950. With a blend of wry humor and hard-boiled atmosphere, The Adventures of Sam Spade holds up as one of the all-time great radio detective shows, thanks in no small part to the man in the title role. In honor of his birthday, we'll hear Duff as Spade in "The Dry Martini Caper" (originally aired on CBS on August 1, 1948) and "The Sugar Kane Caper" (originally aired on CBS on October 3, 1948). We'll also hear him as Captain Philip Kearney in the audition program for the high seas adventure The Voyage of the Scarlet Queen.

We doff our cap to Dick Powell in this birthday celebration of the crooner who reinvented himself as a tough film noir leading man. First, he's private investigator Richard Rogue in "Murder at Minden" from Rogue's Gallery (originally aired on Mutual on January 3, 1946). Then, it's a pair of mysteries starring Powell in his signature radio role as singing gumshoe Richard Diamond, Private Detective: "The Elaine Tanner Case" (originally aired on NBC on February 12, 1950) and "The Carnival Case" (originally aired on NBC on August 16, 1950).

The thrilling and dangerous wartime exploits of the OSS – Office of Strategic Services, the precursor to the CIA – were dramatized on radio in Cloak and Dagger. Tales of adventures behind enemy lines in Europe and the Pacific came to life with stories of civilians, soldiers, and spies on daring missions – knowing in advance they may never return alive. We'll hear "Seeds of Doubt," the story of a spy hunt in occupied Paris, originally aired on NBC on September 15, 1950.

London's criminals have nowhere to hide when Scotland Yard Inspector Peter Black begins his relentless Pursuit. The adventures of Black make for exciting listening as he hunts the evildoers who strike, then fade back into the shadows of their own dark world. Ted de Corsia stars as Black in "Pursuit On Lundy Island" (originally aired on CBS on February 7, 1950) and Ben Wright plays the inspector in "Pursuit and the Ladies of Farthing Street" (originally aired on CBS on September 18, 1951).

Just in time for trick-or-treating, we're bound for Transylvania with Orson Welles and The Mercury Theatre On the Air in a special bonus episode. Welles and his talented troupe of radio players present a chilling and atmospheric radio adaptation of Bram Stoker's Dracula. Welles plays both Arthur Seward and the titular count in a story that's sure to get you in the Halloween spirit. Featuring supporting performances by Agnes Moorehead, George Coulouris, Ray Collins, and Martin Gabel, Dracula originally aired on CBS on July 11, 1938.

The game is afoot with three old time radio mysteries starring the master detective of Baker Street, Sherlock Holmes. Sir Arthur Conan Doyle's immortal character made his debut as a radio sleuth on October 20, 1932, and we're celebrating his anniversary with radio adventures starring three different actors as Holmes. First, Basil Rathbone is Holmes, with Nigel Bruce as Watson, in "The Case of the Limping Ghost" (originally aired on Mutual on September 3, 1945). Next, John Stanley and Alfred Shirley are Holmes and Watson in "The Sussex Vampire" (originally aired on Mutual on December 14, 1947). Finally, John Gielgud and Ralph Richardson star in "The Final Problem" (originally aired on NBC on April 17, 1955), featuring special guest star Orson Welles as Professor Moriarty.

Private detective Michael Shayne came to radio on October 16, 1944 and we're celebrating the anniversary of "the reckless, red-headed Irishman" with two of his radio mysteries. Two of radio's most talented stars – Wally Maher and Cathy Lewis – headline as Shayne and his loyal secretary Phyllis Knight. From 1944 until 1947, the pair starred in stories that blended crime-solving with witty banter. We'll hear "The Murder Trial of Jack Holmes" (originally aired on Mutual on May 21, 1945) and "Dr. Grant's Dilemma" (from August 13, 1945).

William Gargan starred as Barrie Craig, Confidential Investigator – "America's number one detective" – from 1951 to 1955. The actor had a long resume of detective roles on the big and small screens, as well as on radio, but his best on-air work may have been as Craig, the New York-based confidential investigator. We'll hear him in a pair of his radio mysteries: "Death of a Private Eye" (originally aired on NBC on January 2, 1952) and "Fog Over Murder" (originally aired on NBC on October 13, 1953).

For the first two and half years of Dragnet, Sgt. Joe Friday was partnered with Ben Romero, an older mentor and family man voiced by radio veteran Barton Yarborough. With his friendly Texas drawl, Yarborough created a memorable character and a good counterpart to Friday's terse, no-nonsense style. We'll hear Yarborough in action as Ben Romero, alongside Jack Webb as Joe Friday, in "The Big Picture" (originally aired on NBC on December 7, 1950) and "The Big In-Laws" (originally aired on NBC on August 23, 1951).

Pam and Jerry North are the happy couple who can't help but find trouble. Whether it's a corpse or a caper, Mr. and Mrs. North will stumble onto the scene and thwart the plans of evildoers everywhere. We'll hear a pair of adventures starring old time radio's most popular husband and wife detective duos. First, Alice Frost is Pam and Joseph Curtin is Jerry in "The Contagious Confession" (originally aired on NBC on September 22, 1943). Then, the Norths are played by Barbara Britton and Richard Denning in "The Diamond Noose" (a broadcast from the Armed Forces Radio Service).