Scorched Grace by Margot Douaihy

Sister Holiday, a chain-smoking, heavily tattooed, queer nun, puts her amateur sleuthing skills to the test in this "unique and confident" debut crime novel (Gillian Flynn).
When Saint Sebastian's School becomes the target of a shocking arson spree, the Sisters of the Sublime Blood and their surrounding New Orleans community are thrust into chaos.
Patience is a virtue, but punk rocker turned nun Sister Holiday isn't satisfied to just wait around for officials to return her home and sanctuary to its former peace, instead deciding to unveil the mysterious attacker herself. Her investigation leads her down a twisty path of suspicion and secrets, turning her against colleagues, students, and even fellow Sisters along the way. And to piece together the clues of this high-stakes mystery, she must at last reckon with the sins of her own past.
An exciting start to a bold series that breathes new life into the hard-boiled genre, Scorched Grace is a...