Temple of the Red Phoenix

From publisher blurb:

The adventurers are hired to retrieve a powerful artifact from the Temple of the Red Phoenix, a place of worship dedicated to the goddess of fire and rebirth Melverna The Golden Mistress. The temple is guarded by a group of cultists corrupted by their obsession with the Red Phoenix.

Along the way, they will uncover dark secrets about the temple and the cultists' plans for the artifact. Ultimately, they must decide whether to return the artifact to their employer or destroy it, which will have significant consequences for the temple and the goddess herself.