Helm is sent to the ICE (Intelligence and Counter Espionage) Training Headquarters to uncover a traitor in the organisation. Whilst there he meets ICE agent Sheila Sommers, the pilot of the saucer who has been recovered from a Central American jungle with no memory of what happened to the saucer she flew. Due to the electo-magnetic power of the saucer, only a woman is able to fly it, males of the species are killed by the energy.
Helm had worked with Sommers on an assignment where the two had posed as man and wife. When Sommers meets Helm, her memory comes back. Mac, the head of ICE, decides to send Helm and Sommers posing again as his wife undercover as a photographer doing a story on the Montezuma Beer Brewery, whose advertising jingle is the same tune as the anthem of Ortega's political movement.
Along the way, they must deal with Ortega's henchmen, Francesca Madeiros (an operative for Big O, Helm's main nemesis), who poses as a model and seduces Helm, an assassin named Nassim, plus a tough thug named Rocco.
The film was the third of four produced in the late 1960s starring Martin as secret agent Matt Helm. It followed The Silencers and Murderers' Row and like those earlier films followed the approach of being a spoof of the James Bond film series rather than a straight adaptation of Hamilton's novel. It was followed by one more, The Wrecking Crew in 1969.
Interestingly enough, this entry featured a scene similar to a scene from the first Roger Moore James Bond film Live and Let Die in which one of the hero's love interests, in this case Sheila played by Janice Rule, is stripped of her clothes by way of a magnetic gadget.
The film was originally known as The Devastators.
This film is generally considered the weakest of the four Helm films, and is cited in the book The Fifty Worst Films of All Time by Harry and Michael Medved. The Medveds also cited a review of The Ambushers by critic Judith Crist which stated: "The sole distinction of this vomitous mess is that it just about reaches the nadir of witlessness, smirky sexiness and bad taste - and it's dull, dull, dull to boot."
The film earned North American rentals of $4.7 million in 1968.
Hugo Montenegro became the third composer in as many films to do the score for the series. He wrote (along with Herbert Baker who worked on Murderer's Row) the theme song, "The Ambushers," which featured the vocals of Boyce & Hart, two of the songwriters from Murderer's Row. Montenegro went on to compose the score solo for the next Matt Helm film, The Wrecking Crew.