[4][5] The screenplay was written by Edward Chodorov, based on the story[1] "You Were There'" by Thelma Strabel, and allegedly contained uncredited contributions from Marguerite Roberts.

[6] Ann Hamilton, a young woman from a middle class family, meets wealthy businessman Alan Garroway when he comes to visit her scientist father.

Cast notes: Undercurrent was only director Vincente Minnelli's second dramatic film, the first being The Clock, which starred his wife at the time, Judy Garland.

Minnelli's specialty was in directing the kind of glossy musicals that M-G-M's Arthur Freed unit turned out.

Because he trusted producer Pandro S. Berman's judgement in regard to the film's star, Katharine Hepburn – who had already signed on to do the film – Minnelli accepted the assignment; Berman had produced Alice Adams and Stage Door with Hepburn when they both worked for RKO Pictures.

[1] Variety magazine lauded the film and wrote, "Undercurrent is heavy drama with femme appeal...Hepburn sells her role with usual finesse and talent.

"[7] Critic Bosley Crowther of The New York Times also liked the film and wrote, "However, that is Undercurrent-—and you must take it upon its own terms, which are those of theatrical dogmatism, if you hope to endure it at all.

If you do, you may find it gratifying principally because Miss Hepburn gives a crisp and taut performance of a lady overcome by mounting fears and Mr. Taylor, back in films from his war service, accelerates a brooding meanness as her spouse.

You may also find Robert Mitchum fairly appealing in a crumpled, modest way as the culturally oriented brother, even though he appears in only a couple of scenes.

"[8] More recently, critic Dennis Schwartz wrote, "Director Vincente Minnelli...known mostly through his upbeat MGM musicals, changes direction with this tearjerker femme appealing romantic melodrama, that can also be viewed as a heavy going psychological film noir (at least, stylishly noir through the brilliantly dark photography of Karl Freund)...Though overlong and filled with too many misleading clues about which brother is the baddie, the acting is superb, even though both Katharine Hepburn and Robert Mitchum are cast against type (a weak woman and a sensitive man).