Arrow of Fortune (Raiders of the Arcana) by Jacquelyn Benson

A well-behaved lady historian ought to avoid haunted forests… not plunge into them seeking an invincible weapon of the gods. Ellie Mallory didn’t exactly volunteer to prevent the most dangerous artifact of the Ramayana from falling into the wrong hands—but if one has been coerced into an adventure, the least one can do is bring along a few friends. Constance Tyrrell has new daggers stuffed in her garters, a thirst to discover everything India has to offer… and absolutely no interest in Dr. Neil Fairfax, Ellie’s scholarly stepbrother. Meanwhile, Neil finds himself wrangling a magical sword along with his increasingly tangled feelings about a certain doe-eyed danger gnome. Then there’s Adam Bates—handy with a machete, perpetually shirtless, and about to face some unsettling ghosts of his past. Together, they must follow the footsteps of an ancient hero from the festivals of Puri to the shadowy depths of a legendary forest, racing a brutal colonial administrator with allies of his own—including the complicated and mysterious Mr. Jacobs. It will take all Ellie’s resources—from a working knowledge of practical chemistry to a highly excitable dog—to beat a new sort of demon to the place where a holy power has lain hidden for two thousand years… alongside the secret history of the woman at the heart of India’s greatest story. Read more