Joseph Rouletabille, a reporter for a local newspaper, investigates the attempted killing of Mathilde Stangerson, who uses the yellow room of the title as her bedroom. At the time of the revolver shots her room was locked and the windows were barred, but when her father enters after having forced the door, there is no-one there except for Mathilde. So who did it and how did he get away?

Newly married, Mathilde and Robert are honeymooning at a resort owned by their friends Edith and Arthur, the Chateau d'Hercule. But an unpleasant shock is in store for them.