In modern-day Minnesota, Karina "Kina" Zahir longs for a life out from under the thumb of her controlling and emotionally abusive mother. But the family’s financial situation makes it impossible for Kina to move out. 

When Kina and her sister Shay are attacked by a monster cloaked in shadows, they find refuge with Angelus Corde, a secret society of exorcist Christians. But Kina soon realizes that Angelus Corde, and Shay, are more violent than they seem. An encounter with Kina’s "cultist" uncle throws doubt onto Angelus Corde’s doctrines, and Kina begins to question whether all spirits are truly demonic, as Angelus Corde teaches, or if there is room for good in the spiritual world. Fearing for her own life, Kina flees Angelus Corde’s church, vowing to rescue Shay from the cult once she has the means. 

Kina throws herself upon the mercy of Angelus Corde’s blood enemies, the Merchants, an interdimensional group of spiritual peacekeepers. As she fights to gain their trust and become a Merchant alongside her uncle, she must also unlock the magical potential within her own soul. While Kina crosses between dimensions and discovers the mystical world of Provenance, where humans and spirits live in harmony, Angelus Corde gathers strength for their holy war. Alongside former Angelus Corde member Isaac and his Guardian angel, Kina must find both the inner and the outer strength to save Shay and defend herself, or risk losing both her family and her life in the process.