23 Paces to Baker Street (1956)

This mystery featuring an amateur detective obsessed with preventing a kidnapping caught my attention from the first moments and held it throughout. And I didn't figure out whodunit. Van Johnson gives an excellent performance as a man tormenting himself because he is now blind after a terrible accident. His loyal ex-fiancee follows him to London and helps him work through some of his angst while they put themselves in terribly dangerous situations. Highly recommended.