Ruby is terrified to cave to her feelings for Sean and risk him crushing her heart. Sean is pumped to spend a week with Ruby in Paris on their senior class trip, and he'll wait however long until she's ready to take things further.But when Ruby's best friend sneaks out the first night to meet a mysterious French boy, Ruby goes after her with two classmates, but caves to another temptation: attending mystery boy's exclusive party in the Paris catacombs, the intricate web of tunnels beneath the city, home to six million long-dead Parisians. Only they never reach the party.Underground, as something sinister chases them, they get lost in the endless maze of bones, uncovering dark secrets about the catacombs.....and each other. And if they can't find a way out, they'll die in the dark beneath the City of Light. Aboveground, Sean races to find the girl he loves as a media frenzy over the four missing teens begins.From award-winning author and rising YA star Diana Urban comes a twisty tale of four teens lost in the dark beneath the City of Light and the race to find them.