Eugène Ballanchon, a young talented researcher, is constantly persecuted by his rascal parents, with whom he lives, but also in the laboratory, by his boss, whose anger terrorizes him. One day, while testing a truth serum, he made an error in handling and developed a particularly effective laughing gas. He successfully experiments it on his boss. This discovery attracts the attention of Beauchard, the director's secretary, who engages in industrial espionage on behalf of a foreign power. Beauchard instructs the pretty Régine to seduce the innocent Eugène, while the DST sends two inspectors to protect the brilliant inventor from a process which could, we hope in high places, prevent war forever.