London, 1851. The world is fading to gray, and so are its people. Their eye color dulling as they grow older and forget how to dream, hope, or live with honesty. In a colorless world, Adam has chosen to trust only one: a colorful tiger named Cali. Forced to leave his upper-class life behind, he signs a contract he may never escape and joins Circus Paraventi. But when Cali escapes, Adam must learn to rely on others to find her. Nikolai and Bella, two artists who haven't lost their eye color yet, are not only a great help but an even greater challenge. Their lightheartedness and refusal to take anything serious drive Adam to the brink-especially Nikolai, with his grass-green eyes and frustratingly naive optimism. But something about them makes Adam lower his guard and feel more alive, which proves to be incredibly dangerous in a forest with a tiger on the loose.