The Professor is also Professor Jordan in The 39 Steps (1935)Let's note some similarities here:
- Steps features a man thrust by accident into global intrigue when a spy expires on his doorstep and hands him crucial information. Implicated in murder, he flees to relay the information to someone called "the Professor".
- Northwest features a man thrust by accident into global intrigue when he's confused for a secret agent. Implicated in murder, he flees to work out what's going on and winds up having it all explained by someone called "the Professor".
An alternativeThe Professor in Northwest is the same as Professor Jordan, but the Jordan we see in Steps is not the real Jordan. A foreign agent (call van Damm, or whatever you please), adopts the identity of the Professor, a major intelligence operative. He then hatches a ploy to manipulate an innocent civilian (one Richard Hannay) into assassinating the real Jordan, convincing him that Jordan is simply a traitor. Jordan realizes what is happening at the last second, and decides to play along, getting himself "arrested" (to be bailed out later) and killing Mr. Memory in the process, to rob the impersonator of his major source of information, leaving the impersonator only a Pyrrhic Victory.
"van Damm" is also Professor Jordan in The 39 Steps (1935)Building on the above, the false Jordan then assumes the identity of Lester Townsend, while the real Jordan appropriates his impersonator's scheme by using an elaborate ploy involving an innocent passerby.