In this parody of Boston Blackie, Daffy plays Boston Quackie (Friend to those who need no friends, enemy to those who have no enemies). While vacationing in Paris with his girlfriend Mary, Quackie is approached by Inspector Faraway (Porky) who assigns him to deliver a top secret briefcase to a consulate in West Slobovia. However, the briefcase is immediately stolen by the Man in the Green Hat, requiring Quackie to give chase that leads to a spy-filled train.
Tropes appearing in this cartoon:
- Cranial Eruption: After he and Quackie are served coffee, the Man in the Green Hat asks "how many lumps do you want?" Quackie, who likes lots of sugar on his coffee, foolishly says "better make it three lumps." So the Man in the Green Hat pulls out a club and gives Quackie three lumps on his head.
- Follow That Car: After the Man in the Green Hat escapes in a cab, Quackie tells another taxi this. Unfortunately, it takes off before he can get in.
- Handbag of Hurt: Mary manages to incapacitate the Man in the Green Hat by striking him over the head with her purse. It works because she keeps an anvil in it.
- Low Clearance: After leaving Quackie hanging by a mail pole, the Man in the Green Hat ends up getting knocked off the train because he didn't look to see it was going under a wigwag.
- MacGuffin: The briefcase. Quackie has to deliver it to the West Slobovian consulate, then has to get it back from the Man in the Green Hat. When it's delivered, it's revealed to have a bottle of Instant Girl, so the Ambassador could have a date for the Embassy Ball.Quackie: You know, there just might be a market for this.
- Matryoshka Object: Quackie tries to uncover the Man in the Green Hat, who has changed it for a top hat. But when he knocks over the hat, it just uncovers a different hat. Knocking that hat away reveals another hat, and doing it a third time just reveals the same hat as before. After the man gets Quackie with the old "One lump or two" gag, he tips his hat, revealing at last the green hat.
- Person with the Clothing: The Man in the Green Hat.
- Smart Ball: Unlike most cartoons where Daffy is a bungling hero, Boston Quackie actually shows some degree of competence. His suspicion that the man wearing a top hat was actually the Man in the Green Hat in disguise was correct, even if he gets briefly thrown off by multiple hidden hats; and he is Genre Savvy enough to stop a poisoning attempt without even looking away. That being said, he still falls for the old "How many lumps do you want?" gag.
- Tampering with Food and Drink: As Quackie joins the Man in the Green Hat for a drink, a man hidden under the trolley poisons his cup. Without even looking away, Quackie shoots the man under the table, then disposes of the drink into a nearby spittoon, which melts away.
- Thriller on the Express: Quackie follows the Man in the Green Hat to Le Cloak and Dagger Express, where there seems to be a criminal in every berth.