David Niven portrays the character from Baroness Orczy’s story in a stylish, though somewhat insubstantial, adaptation of "The Scarlet Pimpernel." The narrative follows his efforts to rescue French aristocrats facing danger during the Reign of Terror, prompting authorities to assign Cyril Cusack's character, “Chauvelin,” with finding him. Chauvelin uses pressure against the alluring new wife of Sir Percy Blakeney, “Lady Blakeney” (Margaret Leighton), threatening her brother’s life unless she assists in his pursuit. Although she is married to a seemingly frivolous man, one must question whether his outward appearance reflects his true capabilities? Niven performs admirably; the plot maintains a decent pace through intrigue, and Margaret Leighton consistently provides capable performances, even if this isn't among her finest work. While not representative of Powell & Pressburger’s strongest films, it remains an elegant adventure with a touch of humor, culminating in a thrilling final quarter-hour. It might not surpass Leslie Howard’s 1934 version, but Niven seems to have had a good time making it, and I found it enjoyable as well.

Source on TMDB