When a bullying incident sends twelve-year-old Nico Holland over the edge of a cliff into the icy waters of Still Cove, friends Tyler and Emma - and even cool kid Opal - rush to his rescue … only to discover an island hidden in the murky, swirling mists below. Though it appears uninhabited, all four kids can’t quite shake the feeling that what they’ve found is no paradise - especially when they stumble upon an abandoned houseboat with an array of curiosities inside: odd-looking weapons, maps to places they’ve never heard of, and glass jar containing something unidentifiable. As they delve deeper into the unknown, their discoveries - and their lives - begin to intertwine in weird and threatening ways.