The paths of Alwyn and Peter Graham Scott had crossed as early as 1942, when Scott was the young editor of A Modern Miracle (1942). Scott remembers working with Alwyn after the war on Proud City : “Bill and I had to run through each sequence on the Moviola, a rackety and noisy viewing machine then universally used for editing … many many times until he had the precise footage and action written down, and impressed on his fertile brain.” By the end of the 1950s Scott was carving a successful career in television, but he made a rare return to the cinema to direct a B-picture, Devil's Bait (1959). Though cheap, Devil's Bait has considerable merit : tight scripting and direction and convincing characters and relationships, in a tense drama of less than an hour's length. Its director now tends to disclaim it - “I’ve done much better work since” - but Alwyn nevertheless took the trouble to compose an original, meticulous, and well-structured score. The story, an unusual one by Peter Johnston and Diana K. Watson, concerns the baker Frisby (Geoffrey Keen), a gruff, unloving husband to his wife Ellen (Jane Hylton), who takes on the alcoholic rat-catcher Love (Dermot Kelly). As a result of Love's impatience for a drink, cyanide is baked into a single loaf, which is sold on before Frisby and Ellen discover what's happened. There ensues a panicky chase to retrieve the loaf.

This was not Alwyn's first film about rats. His wartime instructional film, Rat Destruction, contains a little moto perpetuo for woodwind (and no strings). The opening mood of Devil's Bait is equally fast, but these rats squeal with clarinet and flute trills, short appoggiaturas, and arpeggios against ostinato strings. A dark mood is created, entirely missing in the earlier documentary, heightened by a dissonance in the woodwind, encouraged by the use of tonics with seconds and sevenths.

In the crucial scene where Love mixes and lays his deadly bait, suspense is tightened by a mixture of musical techniques : low brooding cellos and basses, rising scales, sequencing, trembling dissonant chords, ostinato, pedal points, and rubato. It contains one of the oldest tricks of the cinema, the shock of an unexpected alarm (the baker's wife's dough timer) with the crash as Love drops a saucer in surprise. Sound-effects intelligently enhance the drama of this second feature throughout.