Don't Let Go

(Complete! Two pts. at ending) 2012 version. After a nasty fight between Leo and Raph, Leo leaves the lair and is attacked by the foot. Now feeling the heavy toll of Leo' absence, Donnie, Raph, and Mikey go looking for their lost bro. Only to discover something is terribly wrong with him... will it get passed to them as well? And what will happen to Leo?