Set in a small-town tavern near the edge of an industrial mining settlement, the short opens with weary workers arriving at the end of a long shift. Dust-covered and exhausted, they crowd into the dimly lit saloon where a familiar sight awaits: KOEUB, poised at center stage, delivers a lively musical performance, accompanied by Chirol on piano. Her youthful charm and confident stage presence captivate the audience, bringing a sense of relief and warmth to the room. The short alternates between musical numbers and comical cutaways to Chirol’s exaggerated piano playing. The miners, rejuvenated by the performance, raise their glasses in cheer as the short fades to black.
Keys and Curves is among the earliest B&C shorts to adopt a musical-centered format, likely influenced by the growing popularity of "sound cartoons" in the late 1920s. It showcases KOEUB in a different light—not as a comedic foil, but as a performer with stage charisma, solidifying her role beyond domestic slapstick.
The animation style emphasizes rhythm and timing, especially in the synchronization between Chirol’s piano keys and his animated finger movements. KOEUB’s singing is once again uncredited, yet her melodic lines are more prominent than in previous entries, fueling continued speculation about the voice actress’s identity.
The short stands out for its restrained use of humor and its tonal shift toward sentimentality and admiration, reflecting the studio's experimentation with more atmospheric storytelling during this period.