When the film begins, you learn that one of the smartest men in the world, the Frenchman Professor Gaston Le Beau, is missing. However, he turns out to be an exact double of Sach...and soon some UN officials see Sach and think he's the brilliant guy. Well, even when they soon realize it isn't Le Beau, they decide to bring him as well as Slip and Louie to Paris and pretend they've found the Professor. Not surprisingly, Sach behaves like a cretin and his goofiness is explained away by saying Le Beau has amnesia. Unfortunately, there are some killers who are planning on doing away with the Professor...and soon the real Le Beau shows up as well.
This installment of the Bowery Boys is typical in some ways for the later films in the series in that it's really all about Sach (Huntz Hall), Slip (Leo Gorcey) and Louie (Bernard Gorcey)...plus calling these middle-aged men 'boys' is a bit ridiculous! It's not so typical because the film is a bit goofier than usual, such as the stupid scene involving the Professor's favorite drink (not one of cinema's finer moments). Plus, while Hall playing Sach is ridiculous, his playing the real Frenchman is REALLY over the top! Of course, folks don't expect Shakespeare or an art film when they see the Bowery Boys!!
By the way, I was curious after hearing one of the characters say 'sacre bleu' in the film and I looked up this curse. Apparently, real French folks never say this and it's something foreign films show supposedly French people saying!