Quick recap
Sarah Maas hates swimming, but her parents send her to Camp Cold Lake, a water-sports camp. Her bunkmates Briana, Meg, and Jan treat her badly. To win some sympathy, Sarah fakes a drowning. When she surfaces, the camp is gone, it's snowing, and a see-through girl named Della asks her to be her buddy. Sarah is revived, but Della keeps showing up and tries to get her in the lake. In the woods, Della explains the snakes there killed her, and she wants Sarah to join her. Briana shows up, pulls a snake off Sarah's leg, and saves her. The twist: Briana is a ghost too, killed by Della the summer before. At the end, she walks up holding a snake and asks Sarah to be her buddy forever.
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