Chuck Norris makes his film debut in a small role.
This was the last film of Tate's to be released before her murder at the hands of Charles Manson's followers on August 9, 1969.
Matt Helm is assigned by his secret agency, ICE, to bring down an evil count named Contini, who is trying to collapse the world economy by stealing a billion dollars in gold.
Helm travels to Denmark, where he is given a guide, Freya Carlson, a beautiful but bumbling woman from a Danish tourism bureau.
A pair of Contini's accomplices, the seductive Linka Karensky and Yu-Rang, each attempt to foil Helm's plans. The former is killed in an ambush intended for Helm, the latter in an explosion. On each occasion, Freya's clumsy attempts to assist Matt are helpful, but not particularly appreciated.
McDonald, his chief at ICE, turns up to aid Helm, but is wounded in action. McDonald confides to Helm that the seemingly inept Freya is actually a top secret agent herself, using a clever guise.
They go to Contini's chateau for a showdown, and Helm creates chaos and destruction with a variety of unique gadgets. Contini escapes on a train bound for Luxembourg, but with a minihelicopter, Helm and Freya are able to catch up.
Contini is killed on the train, dropping through a trap door. Successful and alone at last, Helm finally has an opportunity to thank Freya as only he can.Dean Martin as Matt Helm
Elke Sommer as Linka Karensky
Sharon Tate as Freya Carlson
Nancy Kwan as Wen Yu-Rang
Nigel Green as Count Contini
Tina Louise as Lola Medina
John Larch as 'Mac' MacDonald
John Brascia as Karl
Weaver Levy as Kim
Wilhelm von Homburg as Gregor
Bill Saito as Ching
Fuji as Toki
Pepper Martin as Frankie
Mary Ann O'Conner, Hertz Rent-a-Car Girl (uncredited)
Ted H. Jordan as Guard
Whitney Chase as Miss Natural Gas (uncredited)
David Chow as Bartender (uncredited)
Noel Drayton as Man at Downing Street Meeting (uncredited)
Tony Giorgio as Gadget Agent for I.C.E. (uncredited)
Joséphine James as Girl (uncredited)
Kenner G. Kemp as Officer in Hospital Room (uncredited)
John Kowal as Kelly (uncredited)
James Lloyd as Desk Clerk (uncredited)
Byron Morrow as Officer in Hospital Room (uncredited)
Chuck Norris as Man in the House of 7 Joys (uncredited)
Allen Pinson as Page (uncredited)
Bartlett Robinson as President's Aide (uncredited)
Bill M. Ryusaki as Henri (uncredited)
Dick Winslow as Man (uncredited)
J. B. Pick
Vincent Van Lynn
Miscellaneous credits: Bruce Lee as 'Karate Advisor' (choreographer) for the fight scenes. Dean Martin's double is karate champion and stuntman Mike Stone. World karate and kickboxing champion Joe Lewis and American Kenpo founder Ed Parker both had fight scenes with Dean Martin.
The film is the first in the series to not be written or co-written by regular screenwriter Herbert Baker, who was working on Irving Allen's more serious spy film Hammerhead. The film was written by former police reporter and crime novel author William P. McGivern.
Chuck Norris makes his film debut in a small role as a suited nightclub gunman.
Also appearing in the film are Nancy Kwan as Wen Yu-Rang, Tina Louise as Lola Medina, and Nigel Green as the villainous Count Contini.
Helm's chief at ICE, MacDonald, is John Larch in this film, replacing James Gregory, who played the role in the other three films. Gregory said in an interview in Filmfax magazine that he was sent a reduced amount for his fee in the film. He was told that the film was reducing its budget, but Gregory refused to take the lower fee.
This is the only film in the series not to feature Helm's secretary, Lovey Kravesit, played by Beverly Adams, who was also appearing in Hammerhead.
Hugo Montenegro composed the score and Mack David and Frank DeVol wrote the theme song played over the opening and end credits, "House of Seven Joys", which was the working title of the film.
Critical response to this film varies, with some calling it the worst of the series, where it mostly features Helm playing up to glamorous women and the storyline is the bits that join those many encounters together. Also some acting was poor and the film had many minor mistakes in it which should have been edited out, as well as so-so special effects. Others called it the best due to its reduced reliance on outlandish gadgets and story lines. It is also notable for the appearance of Tate and martial arts scenes choreographed by Lee.
The film ends with the announcement of a fifth Matt Helm film, The Ravagers (which would have been based upon Hamilton's 1964 novel of the same title). However, Dean Martin declined to return for another film in the face of a declining box office. When Martin refused to make The Ravagers, Columbia held up Martin's share of the profits on Murderers' Row. The project was then cancelled.
A "Tony Rome Meets Matt Helm" movie with Frank Sinatra reprising the character he had played in the films Tony Rome (1967) and Lady in Cement was also bandied about, but never amounted to anything.
Several years later, a Matt Helm TV series featuring Tony Franciosa was attempted, but it had nothing to do with the movies, and it was unsuccessful. As of 2009, early planning for a new Matt Helm-based film was underway through DreamWorks.