Winter vacation has finally arrived in River Heights, and Nancy, Bess, and George are ready for some chilly outdoor adventures. They spend their frosty days drinking warm hot cocoa, enjoying the snowy winter weather, and building a magnificent snowman named Sherlock, complete with old rubber boots, a bright blue scarf, and a large broccoli nose. The seasonal fun takes a highly mysterious turn when their friend Deirdre starts making strange predictions by reading the floating marshmallows in her hot cocoa. Surprisingly, her sweet and gooey fortunes actually begin coming true one by one. When Sherlock the snowman suddenly vanishes without a single trace, exactly as Deirdre predicted, the girls know they have a real case to solve. You will join the clever Clue Crew as they bundle up tightly in their winter coats and follow the frosty footprints to find their missing frozen friend. Can they solve the baffling mystery of the disappearing snowman and figure out how Deirdre's marshmallow visions are connected before the trail goes completely cold? Grab your best detective gear and get ready to crack the case in this wonderfully chilly winter whodunit.