The boys graduate from a fly-by-night detective school and immediately take on a murder case, that of Franz, a boxer accused of killing his manager. They visit Muir, who shows them the formula which can turn a person invisible. (In homage there is a photo of Claude Rains, the original
Invisible Man, on the wall.) When police arrive to arrest Franz, he injects himself with the serum and vanishes. Franz later explains to Bud & Lou that a mobster, Leonard, killed Franz's manager when he, Franz, refused to throw a fight. The trio scheme to have Lou pretend to be a prizefighter and
entrap Leonard in a similar fix so police will arrest him. All in all, a pleasant film with consistent laughs.
