Seventeen-year-old Anouk has finally caught the break she's been looking for -- she's been chosen to participate in an exclusive program that includes an all-expenses-paid trip to France and a chance to explore the hidden underground Palais du Papillon, or Palace of the Butterfly. Along with four other gifted teenagers, Anouk will be one of the first people to set foot in the palace in more than two hundred years. But the expedition is not all it seems. The students' supposed benefactors are trying to kill them. And so is the palace itself, which is filled with deadly traps and invisible monsters. Can Anouk and the others figure out how to work together and escape? Bachmann's masterful scene-building alternates between Anouk's flight through the palace and the struggles of Aurélie, who escaped the French Revolution by fleeing into the Palais du Papillon in 1789.