Bourbon Street Beat

Bourbon Street Beat was a private detective series which ran on the ABC network from 1959 through 1960. It featured Andrew Duggan as Cal Calhoun, Richard Long as Rex Randolph, Van Williams as Kenny Madison, and Arlene Howell as Melody Lee Mercer (the secretary at the New Orleans detective agency in which they all worked).

The series was one of several Warner Bros. detective shows which aired on ABC during this era, but Bourbon Street Beat was not as successful as the others (except as a title which sticks in everyone's mind).

When the series ended, the character of Rex Randolph moved to 77 Sunset Strip, and the character of Kenny Madison moved to the spin-off Surfside 6, which aired in the Bourbon Street Beat time slot the following season.

Only Andrew Duggan's character, Cal Calhoun, immediately disappeared from the screen upon the show's cancellation, although viewers probably barely noticed, since the then-ubiquitous Duggan was constantly appearing on so many different television series in other roles.
From: Wikipedia.org

Bourbon Street Beat opening

Linked from nostalgia and retrospection post:

• CLASSIC TV — B