The following version of the book was used to create this study guide: Ruby, Laura, Thirteen Doorways, Wolves Behind Them All. HarperCollins, New York, NY, 2019. Kindle AZW file.

In Thirteen Doorways, Wolves Behind Them All, a novel by Laura Ruby, Pearl Brownlow spends a lot of time at the Guardian Angels Orphanage in Chicago. She talks to the children there, even though most do not register her presence at all. Pearl is a ghost who has been dead more than two decades, and she is not aware of what drives her to spend so much time with the children, especially the babies. She believes she is a victim of the flu pandemic of 1918, but her memories are vague and pieced together. She often stops at a particular blue house and watches the young man and woman inside, though she is careful not to watch too much because the memories are painful. The truth about Pearl's life comes to her in pieces, partly through her interaction with a young orphan named Frankie and partly by a chance encounter that brings back her memories.

Pearl was a beautiful young girl who was basically a pawn in a deal made between two bankers, her father and Charles Kent. Their deal was partly business but included that Pearl would marry Charles. Pearl, however, fell in love with a Chinese boy – a romance that was not acceptable in this time and that was forbidden in the Brownlow's social circle. The baby born of that love was taken from Pearl and now lives in the blue house. Her lover was beaten and sent away. Charles still planned to marry Pearl, but she met his brutality. He sent her to a mental asylum. When she returned home, her brothers were bitter because of the shame and the financial ruin she had caused. Then, her younger brother watched as her older brother drowned.

The ghost of Pearl learns some of these facts through her interaction with Frankie Mazza, a girl living in the orphanage where her father, Gaspare, visits on Sundays, bringing sandwiches and sometimes his girlfriend, Ada. Frankie is shocked when Gaspare announces he and Ada are married and that he is taking her children (also living in the orphanage) and Frankie's older brother to live with them in Colorado, leaving Frankie and her younger sister, Toni, in the orphanage. Frankie is furious but soon finds hope for her future though love that blossoms with an orphan named Sam. Both Sam and Vito are sent to war, and Frankie feels her hope dies along with Sam. When the nuns learn of the illicit love affair, they turn Frankie and Toni out of the orphanage. Gaspare, having returned to Chicago, reluctantly takes them into his home.

Frankie and Toni endure their stepmother's constant disapproval and ire. Gaspare has told them their mother died in childbirth, but an aunt reveals that she is actually alive in a mental asylum. Frankie begins to make plans to break free of their father as the war comes to an end and Vito pledges they are family. She begins work at a diner where she can save more money. She meets a man named Ray who reminds her that she can hope for a future for herself. Soon, Frankie and Toni are living on their own as Pearl continues to watch over them.