A classic whodunit crime story, 'The Man Who Knew' is about the death of a rich South Africa magnate, dealing with diamonds. The actual man who knows so much is Saul Arthur Mann, a walking encyclopedia and the constant envy of Scotland Yard. Wallace’s narrative pace is slow at times, hectic at others, but the overall effect is one of a decent detective novel with a lot of irony and parallel mysteries all around the place. Resembling the style of Agatha Christie, the complicated situations and style of Wallace is a perfect read for any diehard fan of detective fiction.