Solar Warden by Peter Fuller

You've heard the expression, this is the stuff of nightmares … You have no idea. The Solar Warden team is targeted like never before. New enemy craft creates dangerous challenges across the fleet with deadly results. A new alien threat sets its sights on Scarecrow and anyone who gets in its way–friends and loved ones are not immune. Nothing in the Solar Warden arsenal can defend against this new, supernatural threat. Scarecrow and his comrades must hope they can enlist the aid of a supernatural ally of their own in time.