After an avalanche killed happily married couple George Kerby (Robert Sterling) and Marion Kerby (Anne Jeffreys) during their fifth anniversary vacation in Switzerland, their ghosts returned to haunt their home which had since been sold to a stuffy banker named Cosmo Topper (Leo G. Carroll). Accompanying the Kerby's was an inebriated mountain rescue dog named Neil who also died on the slopes during the avalanche.

When the Kerby's first met Neil, Marian commented, "First time I saw a St. Bernard who couldn't carry its own liquor." Neil preferred drinking martinis (olive's up) and brandy.

Neil's real name is Buck. Buck was raised by Beatrice Knight of the Sanctuary Kennels in Oregon.

The series is based on the movie Topper (1937) which was inspired by the novel "The Jovial Ghosts" written by Thorne Smith. In the novel, the dog is called Oscar. TOPPER was television's first fantasy series.

In the film Topper (1937) starring Cary Grant, the Kerby's owned a wire terrier named Mr. Atlas (played by Skippy) who later played "Asta" in the TV series THE THIN MAN.