Whirlwind casts Gene Autry as a member of the postal police who with sidekick Smiley Burnette is after Thurston Hall who is the local Ben Cartwright in his area, but who is also involved in a lot of criminal enterprises. Robbing the US mail will always get the federal government's interest.
Autry is going to need all the help he can get even if it is Smiley Burnette. Hall has the law sewed up nice in his pocket with county attorney Harry Lauter and sheriff Harry Harvey on the pad. In fact Lauter has some nasty dirt on Hall himself.
Turns out his one weakness is his niece Gail Davis who Gene charms with a bit of cowboy music. It also turns out that Hall has done her the dirtiest of all.