Fourteen-year-old Avery Armisted and sixteen-year-old Kayla Butts, once good friends, begrudgingly travel to Spain together for a summer vacation where they uncover a secret their families kept hidden from them their entire lives.

While investigating a series of old, spooky photos of a seemingly transparent boy for their friend Ree, who lives above a funeral home, best friends Colin and Neveah follow the clues to solve this mystery from the Great Depression.

Told from separate viewpoints, this is the story of Chess, Emma, and Finn Greystone, ages twelve, ten, and eight, who investigate why their mother went missing and uncover their ties to an alternate world.