The secret hour is beginning to crumble and the darklings are preparing to feed for the first time in centuries. The Midnighters look to Rex for a plan, but his dark side is threatening to overpower him. Melissa can taste his animal instincts leading him into taking greater and greater risks. But as Bixby faces the darklings' hunger, will it be Rex or another Midnighter who will to make the final sacrifice to save the ones they love?