The young man sings the titular "forgotten melody" (Już nie zapomnisz mnie), but when a series of misunderstandings arise between the couple, their feelings fade and they forget the lyrics of the song.

Helenka's father, Bogusław Rolicz (Antoni Fertner) – the president of a cosmetics company – uses the "forgotten melody" to remember the recipe for his invention and protect it from theft by a competitor in the industry, Roxy.

Jerzy Toeplitz wrote that it was "the only successful cultural musical comedy in the entire pre-war Polish film industry (...) ", which "had a well-constructed plot, humor, and charm".

After reading the message about the urgent need for a meeting, the irritated professor throws the note out the window directly into Stefan's hands, who was waiting at the school gate.

[2] At the same time, Bogusław Rolicz, in the final stages of preparing to present his latest incredible achievement to the supervisory board – chocolate-flavored soap that bounces like a ball after being wetted – fears that his competitor, Mr. Roxy, will steal the recipe and take all the profits.

At one point, Helenka plays the song Stefan sang for her, prompting the industrialist to come up with the formula words set to a catchy melody and begin making progress in memorization.

[4] Professor Frankiewicz explains the recent mistake to Lili Fontelli, then, unaccustomed to alcohol, at her urging, he drinks a cocktail, which suddenly worsens his health.

President Rolicz witnesses the inappropriate behavior of the professor and is shocked by his daughter's presence with a stranger at the dance hall, and to top it off, his secretary convinces him that Stefan is the son of a competitor in the industry.

During a board meeting, Rolicz forgets the memorized formula, and an anxious Helenka fails to remember Stefan's song, so she must – not without joy – restore him to favor.

[6] In the role of boarders, besides Grossówna, Andrzejewska, and Radojewska, background actors, who were students at Tacjanna Wysocka's [pl] dance school (advertised in the press as "the most beautiful Warsaw women"), also appeared.

[19] Anna Zahorska from Kultura appreciated the fairly cohesive script, the wit of some scenes, and the actors' performances (with the exception of Żabczyński, who apart from his looks, did not impress with much else, moving as if indifferent).

These trivialities, moralisms, displays of human inferiority, the incredibly low level of the characters, the poor atmosphere of each script, this mixing of school with dancing always characterizes films made in Poland.

Some of them compared the beginning of Zapomniana melodia, with the schoolgirls singing while kayaking, to the first scenes of Mad About Music (1938, directed by Norman Taurog) with Deanna Durbin at the helm, where a group of boarders sang while riding bicycles on a wide avenue.

", was of the opinion that: Grossówna and Andrzejewska here appear as if racing nobly for the palm of precedence, which must be awarded to each of them, as they created two distinct types of boarders: the scatterbrain and the romantic.

The burden of comedy is divided among several stars borrowed from the stage: on the reliable Fertner, on the professionally seconding him in the amusing role of the devoted secretary Sielański, who in turn is always perfectly matched even in bit parts by Orwid and Grabowski.

[23] Leszek Armatys dedicated an essay to the production, in which he stated that the smoothly executed Zapomniana melodia brought relaxation and cheerfulness to Poles during the increasingly real threat of war.

Additionally, he appreciated the skillful use of the formula of American sentimental comedies, driving the action with continuous misunderstandings, and using musical scenes (the jazzy vocal-dance improvisation of Frère Jacques canon by the girls on assembled school benches).

In summarizing his statement, he complained about escapism, shallowness, and vulgarity of some comedic devices, but above all, he praised Zapomniana melodia because next to a few other films made at the end of the Second Polish Republic, it was a work (among comedies – the only one!)