Bloodlust - S4.E11

When a young teenage girl collapses and dies in her nightgown at the fountain at The Gordon Academy for Young Women, Ogden and Murdoch are called in to investigate. Why had she snuck out? She had lost a lot of blood, but only a trickle was there when they found her? And who is the mysterious lone figure that seems to haunt the school at night? The schoolgirl witnesses tell tales of trances and beautiful pale-skinned young men, and soon people begin to believe that vampirism is behind the murder...