Mr. Moto goes undercover to find out who has been blowing up oil wells and trying to gain total control of all the oil leases from a petroleum-rich Middle Eastern country.

Like the play from which it derived, the film tells of the early struggles of composer Edvard Grieg and his attempts to develop an authentic Norwegian national music. It stars Toralv Maurstad as Grieg and features an international cast including Florence Henderson, Christina Schollin, Robert Morley, Harry Secombe, Oskar Homolka, Edward G. Robinson and Frank Porretta (as Rikard Nordraak). Filmed in Super Panavision 70 by Davis Boulton and presented in single-camera Cinerama in some countries, it was an attempt to capitalise on the success of The Sound of Music.

In this sequel to Treasure Island, Long John hopes to rescue his friend Jim from a rival pirate and return for more treasure.