Sisterhood is difficult for Su and Emerald. Su leads a sheltered, moneyed life as the picture-perfect wife of a conservative politician in Singapore. Emerald is a nihilistic sugar baby in New York, living from whim to whim and using her charms to make ends meet. But they share a secret: once, they were snakes, basking under a full moon in Tang dynasty China.

A thousand years later, their mysterious history is the only thing still binding them together. When Emerald experiences a violent encounter in Central Park and Su boards the next flight to New York, the two reach a tenuous reconciliation for the first time in decades. Su convinces Emerald to move to Singapore so she can keep an eye on herbut she soon begins to worry that Emeralds irrepressible behavior will out them both, in a sparkling, affluent city where everything runs like clockwork and any deviation from the norm is automatically suspect.