When they are home alone, Henry and Henrietta discover a key in one of the cupboards they have managed to open, which unlocks the door to Grandfather's bedroom.
One morning Henrietta mysteriously disappears, and Henry discovers a journal entry that tells him how the cupboards work.
They witness a group of people with wolves called "witch-dogs" kill almost all of the guests at a ball, but they escape.
The children push her through the cupboard into an unnamed place, and Dotty and Frank are rushed to the hospital where they are healed.
This creature called a radiant, was the one banging against his cupboard, causing it to break through the plaster at the beginning of the book.