The plot, according to production company Front Street Pictures:

A reimagining of the classic Robin Hood tale merges the elements of magic and medieval romance. The Sheriff of Nottingham has targeted Robin and his band of heroes dwelling within Sherwood Forest. To destroy his enemies, the Sheriff unleashes an unstoppable creature that transforms at night into Alina, a striking woman. Robin must find a cure for Alina before her terror spreads, all the while keeping his childhood love Maid Marion out of harm’s way.

“Smallville”‘s Lois Lane, Erica Durance, takes on the role of Maid Marian, and who better to play the monster-conjuring foil to Robin Hood than none other than the original Warlock Julian Sands? None!

Look for Robin Hood: Beyond Sherwood presumably sometime later this year. (source)