"Foreign Spies" refers to the two foreign spies from "Serum to Codfish Cove".
The two spies wanted Donald Duck to transfer (without his knowledge) some stolen blueprints to Codfish Cove. The spies switch a bottle of serum with one containing the blueprints. Donald takes the package and starts skiing, while one of the spies follows him.
Donald is tired and considers going back and admitting that he has no skiing experience. The spy shoots to force him to continue.
Huey, Dewey and Louie Duck find their exhausted uncle unconscious in the snow outside Codfish Cove and the spy about to attack him. They knock the spy out, replace the blueprints with the serum and wake Donald up with a gunshot. Donald manages to arrive to the hospital.