The plot involves a disgruntled employee's attempt to kill his boss at a high-tech defense contractor by putting a bomb in a suitcase and substituting it for an identical piece of luggage aboard the company plane when the boss and his two partners head off to Cape Canaveral to oversee a rocket test. The bomb is discovered in flight and defused by an engineer on board and the FBI are called on a "Code 98" (sabotage) and proceed to investigate, following each piece of evidence and each lead until they're able to identify the culprit, if not exactly the motive, and then set out to apprehend him. At no point is the audience kept in the dark about anything. We see the bomb-maker prepare his work in the film's very first shot. The moderate suspense comes from waiting for the FBI to get through all their dead ends and red herrings and catch up to him.
It's not the most exciting FBI thriller I've ever seen. The emphasis is on method, not action. There's a narrator who guides us in his stentorian tones through each step of the investigation. The villain is played by character actor Vaughn Taylor, who usually played bankers or store clerks in westerns and small-town dramas. Here he plays the electrical maintenance supervisor at Amertronic, the defense contractor, and blends in with the scenery so well he never looks like a suspect. At one point in the film, when things get confrontational, it seems way out of character for him. Still, in real life, there are numerous crimes, hostage situations, and acts of sabotage carried out for the most banal motives by some of the most unprepossessing perpetrators, so this plot doesn't seem far-fetched at all.
There is a romantic triangle subplot involving the boss's wife and another key employee that seems to have been inserted to provide a false lead and winds up slowing the film down quite a bit, but the good thing about it is that it injects some moments of human realism into the otherwise overly modulated proceedings, and the three actors involved, Andrew Duggan as the boss, Kathleen Crowley as his wife and Jack Cassidy as the employee, stand out because of it. Cassidy has one great bit where he storms out of the office announcing that the others will hear from his lawyer and it's a moment of honest human emotion in a film where pretty much everyone else is on their most dutiful behavior. Cassidy's presence in the cast is, in fact, what excited me the most when I first saw the film. I had seen him in the Broadway musical, SHE LOVES ME, the previous summer when my parents took me to my first Broadway show.
Most of the film takes place in San Francisco, with scenes set in Las Vegas, Cape Canaveral, and Washington D.C. There is some location shooting in Las Vegas and several scenes that appear to have been shot at FBI headquarters in D.C. The film was made with the full cooperation of the FBI and J. Edgar Hoover himself even makes a cameo appearance at the end. Although this film didn't lead directly to a TV series, Warner Bros. did indeed fine tune the premise and eventually produced "The F.B.I.," which premiered on TV the following year (1965) and had a successful nine-year run. (I once visited the set of "The F.B.I." on a trip to Warner Bros. in January 1974.) One cast member of this film, William Reynolds, who plays Special Agent Fox in the San Francisco office, went on to play one of the lead characters in the TV series. In the film, Fox keeps hitting on an attractive secretary in the office in a running gag that seems not to have violated any FBI workplace behavioral codes.
The thoroughly professional cast is led by Jack Kelly ("Maverick"), Ray Danton (THE RISE AND FALL OF LEGS DIAMOND), Philip Carey ("Laredo"), and the aforementioned Andrew Duggan ("Bourbon Street Beat"), all of whom were regulars in Warner productions. Kelly, Danton and Duggan play the three partners who started up Amertronic and are all on the plane when the bomb is discovered, while Carey plays the top FBI agent assigned to the case. There are long stretches without the three main characters, during which the FBI agents are shown going about their business. The cast is filled with a lot of familiar faces including, in addition to those already mentioned, Merry Anders, Ken Lynch, Ross Elliott, Eddie Ryder, James Seay, John Baer and several others whose names I don't know and are not listed in IMDb's cast list but whom I've seen in multiple movies and TV shows from the 1950s and '60s.