Inspector French's Greatest Case is a 1924 mystery detective novel by Freeman Wills Crofts. It in his series of novels featuring Inspector French, a Scotland Yard detective of the Golden Age known for his methodical technique. Like much of the following series the plot mixes the traditional form of the puzzle mystery with that of a police procedural. French has to carefully study railway and shipping timetables and crack a cipher in order to solve his case. Source: Wikipedia (en)