After Marissa Tahy returns home to Santa Fe, she is haunted by visions and glimpses of danger no one else sees: Old Man Gloom in his true form. For over a century, people have burned their troubles in the spirit's effigy at the Zozobra festival, making the spirit angrier and more powerful. This year, Old Man Gloom demands his due. The vengeful spirit targets those Marissa loves. Even when Marissa discovers the secret history binding her family to Zozobra, joining their forces may not be enough to prevent the furious spirit from burying Santa Fe beneath an avalanche of misery.