The 39 Steps is a melodrama adapted from the 1915 novel by John Buchan and the 1935 film by Alfred Hitchcock.
Sespence still riegns, but for the fact only four actor recreate the entirety of the 1935 adventure film The 39 Steps! Thus the film's serious spy story is played mainly for laughs, and the script is full of allusions to (and puns on the titles of) other Alfred Hitchcock films, including Strangers on a Train, Rear Window, Psycho, Vertigo and North by Northwest.