The Professor (Leo G. Carroll)’s Timeline and Summary

In a meeting with other officials, the Professor reveals to the audience that there's no George Kaplan; he's a fake agent, a decoy meant deflect attention from the agency's "Number One." We'll eventually learn that this Number One is Eve Kaplan.
When other agents suggest that it's "callous" to let Thornhill fend for himself, the Professor disagrees, emphasizing the importance of their mission.
The Professor meets Thornhill at the airport outside Chicago, after ordering police to bring him there.
He explains to Thornhill that George Kaplan's not real and that Eve's now in great danger.
The Professor enlists Kaplan in a plan to clear Eve of suspicion by allowing her to "kill" him.
Just in time, the Professor orders the shooting of Leonard, who's about to kill Thornhill and Eve. He compliments the sergeant who's fired the shot on his marksmanship.