According to the game's official Steam description,

Banishers: Ghost of New Eden is set in New Eden, 1695. Antea Duarte and Red mac Raith are lovers and Banishers, ghost-hunters who vowed to protect the living from the threat of lingering ghosts and specters. Following a disastrous last mission, Antea is fatally wounded, becoming one of the spirits she loathes. In the haunted wilds of North America, the couple desperately searches for a way to liberate Antea from her new plight.

Immerse yourself in a beautiful, intimate and powerful story between two fated lovers. As Banishers, enter the lives of New Eden’s communities and solve haunting cases in a mystical, lore-rich world plagued with supernatural creatures and ancient secrets. Use your wits or combine Antea’s spiritual powers and Red’s arsenal to defeat and banish the souls tormenting the living.