Danger Zone is an odd little double-truck of a movie; it tells two entirely independent stories, one after the other, though with three recurring characters. The only plausible explanation is that the stories were pilot episodes of a television series that never got picked up, but were salvaged by packaging as a twofer and farming out as a programmer to theater chains.
A troubleshooter who earns his keep renting boats on the San Francisco waterfront, O'Brian (Hugh Beaumont) picks up spare change by taking on freelance assignments; his usual fee is $50, for which he is usually set up. He shares his nautical digs with an old souse called (of course) The Professor (Edward Brophy), a Runyonesque character with a Thesaurus instead of a voicebox -- he never says "I had the chance" if he can proclaim "The opportunity befell me." Then there's the dim-witted and antagonistic police detective (Richard Travis), always ready to clap the cuffs on Beaumont just before the truth emerges.
Neither of the stories -- the first about a woman who pays Beaumont to bid an exorbitant amount on a locked suitcase that turns out to contain a saxophone, the second about a private detective (Tom Neal, of Detour notoriety) who sets up Beaumont as correspondent, and murderer, in a society divorce case -- gets worked out in any satisfying way. The half-hour allotted to each allows little room for extra characters or unexpected bends in the road (television was to prove that the most successful mystery/detective shows thrived in a hour format). Danger Zone, viewed as early television, is perhaps a tad better than such pioneers as Martin Kane, Private Eye -- at least it's filmed, not done live in studio -- but was nonetheless passed over by the networks in 1951. Beaumont would have to wait six more years, until Leave It To Beaver, to hit his personal jackpot.