Two traveling salesmen (guess who) arrive in the lawless frontier town of Wagon Gap where the outlaw boss Gordon Jones and citizen's committee head William Ching are in a power struggle. Poor inept Costello winds up getting framed for a murder and he and Abbott are both about to be hung when Ching discovers a law in Montana Territory about a man who causes the death of another is responsible for the deceased's debts and family. Costello takes the responsibility.
He soon thinks capital punishment even the extralegal kind might be preferable to dealing with Marjorie Main and her squalling band of kids. Think of Costello inheriting the Kettle clan if Pa Kettle had met his demise at Costello's hands and you have some idea what Costello is going through.
But quite by accident it's discovered that Costello has carte blanche in Wagon Gap because no one wants to see any harm come to him or else they might inherit Marjorie Main. Costello carries a picture of her and the clan close to his heart and it's more valuable than a Sherman Tank would have been. He has a very funny scene cooling down a town drunk played by Dewey Robinson after he's made sheriff.
Marjorie Main with her own brand of rustic humor does not yield the film to Bud and Lou. You might also like the performance of George Cleveland as a judge not unlike Samuel S. Hinds in Destry Rides Again.
In fact the whole film has a lot of similarity to Destry and no surprise there since this was originally supposed to be a more serious story that was to have starred James Stewart. When he passed on it, it was rewritten for Abbott and Costello.
The Wistful Widow of Wagon Gap should appeal to both fans of the Kettle family and those of Bud and Lou. Between them they accounted for a big portion of what counted as profits for Universal Studios.