Viola (Peggy Ashcroft) and Sebastian (Basil Langton) are look-a-like fraternal twins, separated by a shipwreck. Viola lands in Illyria, where she disguises herself like her brother and goes into the service of Duke Orsino (Esmond Knight). Orsino sends her to help him woo the Lady Olivia (Vera Lindsay), who doesn't want the Duke, but finds that she likes the new messenger the Duke is sending. Then, of course, Viola's brother shows up, and merry hell breaks loose. Meanwhile, Olivia's uncle and his cohorts are trying to find some way to get back at Olivia's officious majordomo, Malvolio (George Hayes).