When sixteen-year-old Abigail's mother dies in Scotland—leaving a faded photo, a weirdly cryptic letter, and a one-way ticket to America—she feels nothing. Why should she? Her mother abandoned her as a baby to grow up on an antinuclear commune and then in ugly foster homes. But the letter is a surprise in more ways than one: her father is living in California. What's more, she has an eighteen-year-old sister, Becky. And the two are expecting Abigail to move in with them.

While struggling to overcome her natural suspicions of a note from beyond the grave—not to mention anything positive—Abigail tries to fit in with her strange, new American family: a distant father with a closed past, a too-perfect stepmother, and most puzzling of all, her long-lost sister. Becky sweeps Abigail into a shadowy underground movement involving clandestine street art, jailbreaks, and a bizarre double life. Soon Abigail uncovers something unimaginable: a plot with vast implications—one that is aimed not only at controlling her sister, but the behavior of rebellious teens across the globe.