A twelve-year-old boy's life changes when his grandmother comes from India to live with the family in Mariposa, an island country known for its butterflies, that is becoming hostile to immigrants. Before his grandmother moved from India to the island of Mariposa, Muki Krishnan’s life was good. But now? He has to share his bedroom with Paati, his grandmother, who snores like a bulldozer and wakes him up at dawn to do yoga. Paati’s arrival coincides with even bigger changes in Mariposa. The president divides citizens into Butterflies—families who have lived in Mariposa for three generations—and Moths, who, like Muki’s family, are more recent immigrants. The changes are small at first. But then Muki and his friends find a camp being built to imprison Moths before sending them away. Soon after, his Paati is captured and taken there. While devising Paati’s escape, Muki discovers that a secret rebellion is underway, and as he digs deeper, he realizes that rescuing Paati will be the fight of his life.