The titular Marie-Louise is a young French lass who is evacuated to Switzerland when her country is overrun by the Nazis. Suffering a nervous breakdown, she is given comfort and shelter by a wealthy family. Unfortunately, living in the lap of luxury makes Marie-Louise hesitant to return home to her mother and war torn home. Eventually the girl comes to her senses, but it isn't easy.

A few leagues from Seldwyla, in the Zurich countryside, two children, Sali Mantz and Vreneli Marti, form an inseparable pair of playmates. Unfortunately, their farming parents, who have always been friends, are at odds with each other over the purchase of an adjoining field.Sali and Vreneli don't see each other again until much later and fall in love, but their parents still hate each other fiercely. Despite everything, the young couple will try to live their forbidden love.

If any one man is responsible for the rejuvenation of the postwar Swiss film industry, that man was director Leopold Lindtberg. Matto Regiert (Madness Rules) was co-adapted for the screen by Lindtberg from a novel by Friedrich Glauser. Heinrich Gretler stars as Police Constable Studer, the hero of several of Glauser's most popular works. This time, Studer must solve the murder of the director of an insane asylum -- and it's not (surprise, surprise) the most likely suspect, manic-depressive patient Herbert Caplaun. For box-office purposes, Matto Regiert stresses a romantic subplot involving Caplaun and nurse Irma Wasem.

While on a longer business trip, a wannabe poet urges his beautiful but more simple wife to answer his overly swollen love letters. With no idea how to respond she forwards the letters to a new young school teacher to use his answers instead...