Buffy

When Willow's volunteer work at an oil spill leads her to rescue a selkie, the gang is happy to help the magical seal-girl. But Buffy's slayer instincts are on high alert, and she can't shake the feeling that their new guest isn't as innocent as she seems. To make matters worse, the spill has also unleashed deadly, mermaid-like creatures from the deep, and they're hunting for prey along the coast of Sunnydale.