Employed in a beauty salon, Amédée must undergo a pentothal injection. The dose is too strong; suddenly Amédée reveals the truth to everyone; to clients of the institute; to his cheating wife; to his boss that he robs; to the tax collector; etc. When the effects of the truth serum wear off, everyone returns contentedly to their little swamp.

Loiseau the pharmacist mistakenly mixes potassium cyanide into a batch of cough syrup and sells five bottles. With horror he discovers his mistake and sets out to find the buyers. He finds only four. The fifth, not a regular customer, comes back to the pharmacy...