Exorcizamus Te: Ceiba Pentandra The Silk Cotton Tree (Book 2) by Neel Latchman

Alister and James find themselves smack in the middle of a war that has been ongoing for generations between good and evil. After saving a small village from a Churile, Alister, and James glimpse what kind of evil hides in the shadows. With the last of the line of Eques Famis destroyed, the Harbinger makes its appearance on the twin islands of Trinidad and Tobago. The boys quickly realize they are in over their heads when the entire island begins to smoke because of the mere presence of the Harbinger. A Soucouyant, a bloodthirsty fire demon, she sheds her skin under the cover of nightfall and wreaks havoc on the twin islands. Alister and James get caught in the crossfire when this epic battle between the hunters and the creatures of the darkness commences.