The book is The Conjure Wife, the 1943 debut novel by Fritz Lieber Jr., who would go on to become one of the more prolific American fantasy and science-fiction authors. It involves a college professor who learns that he owes much of his success to his wife's supernatural assistance. After demanding she stop, he must face the unpleasant consequences of going it alone. Ray will write and direct, though it's not clear if The Conjure Wife will sneak ahead of the fact-based project Ray currently has in the works -- How to Rig an Election, the story of a political operative who swung a 2002 Senate race using some not-entirely-ethical means.
This is actually not Ray's first foray into the fantastic, though with any luck it'll be better than Volcano, which Ray co-wrote back in 1997, and Suspect Zero, which he co-wrote with Zak Penn in 2004. Nor is this the first cinematic go-round for The Conjure Wife, which has been adapted as Weird Woman (with Lon Chaney!), Night of the Eagle (a.k.a. Burn, Witch, Burn!), and Witches' Brew, none of which, sadly, I've seen.