At the end of “Insidious: The Red Door,” the film reveals the significance of the red door as a key to unlocking the repressed memories of Dalton and his father, Josh. The door symbolizes the unspoken fears and the chronic illness that the Lambert family has been silently dealing with. In a climactic moment, Josh realizes that the door is being covered in paint, an act done by Dalton, and they work together to confront and overcome their fears. The ending suggests a resolution to their haunting experiences, with Josh and Dalton determined to save each other from the terror that has plagued their family