Challenge of the Yukon is now better known as Sergeant Preston of the Yukon, its later radio and (ultimately) television title. It began as a fifteen-minute show on Detroit's WXYZ radio station (now WXYT) on February 3, 1938.
Following the success of the station's The Lone Ranger and The Green Hornet programs, station owner George Trendle thought the time was ripe for an adventure show featuring a dog -- not your wimpy Lassie-type dog, mind you, but a hard-working dog. A couple of items then came into play. First, Renfrew of the Royal Mounted, a radio show based on the character created by Laurie York Erskine for a series of popular novels aired beginning in 1936, paving the way for "Northwesterns" and, second, Zane Grey's 1915 novel The Lone Star Ranger eventually influenced the creation of The Lone Ranger by Trendle and Fran Striker. Then in 1935, a man named Stephen Slesinger created the comic strip Zane Gray's King of the Royal Mounted about a Canadian Mountie named Dave King. The time was right for another show about a Mountie who always gets his man. It should be noted that Renfrew (in the movies, at least) had a canine companion. So there was room in the new series Trendle proposed for a hard-working dog. Writer Tom Dougall, influenced by the poems of Robert Service, decided to make the dog a husky and wanted to name him "Mogo" but Trendle changed the name to King in a sort of homage to Zane Gray.
So we had the location (Canada, specifically the Yukon Territory), and for plot purposes a time (the 1890's -- the gold rush would provide plenty of fodder for plots), and we had a dog (a husky named King, full name Yukon King), and we had a Mountie protagonist (who was eventually named Sergeant Frank Preston). (Preston's horse, Rex, always played second fiddle to Yukon King.)
Frank Preston was originally played by Jay Michael (the original Butch Cavendish of Lone Ranger nemesis fame), followed by Paul Sutton, then Bruce Beemer, and then Paul Sutton again. Yukon King was voiced by sound effects man Dewey Cole; actor Ted Johnson took over voicing after Cole's death. The show itself ran through 1947 when it moved to television from 1947 to 1949. The radio show was resurrected in 1949 and ran until 1955, when it again appeared on television. The role of Preston on television was played by Richard Simmons and the character's first name was evidently changed from Frank to William.
"Murder on the Mountain" aired on February 19, 1953.
And I have to end this post by saying, "Well, King, this case is closed."