Gowri and Gopika are twins, but they have never agreed on a single thing. Gowri fills every notebook with monsters instead of homework. Gopika checks everything twice, just to be sure.
They bicker about everything, right up until a monsoon storm traps them inside a crumbling old temple no one visits anymore. Inside, hidden behind a wall that shouldn't move, they find a small round chamber that has been waiting for them far longer than either has been alive.
A stone soldier stands frozen there, caught mid-battle, as if time itself stopped around him centuries ago. Beside him glows something small, dark, and ancient. Gowri touches it. She shouldn't have. Within days, the sisters discover powers neither can control, gifts tracing back to a vow made long before their family had a name for it. Somewhere in the hills, an ancient darkness is beginning to stir. And a night is coming when everything their family has guarded for centuries will finally come due.
Guided by a priest who isn't entirely what he seems, and racing against a secret in their mother's oldest diary, the sisters must learn the hardest lesson of all: whatever is coming cannot be faced by one sister alone. Some legacies are too big to carry by yourself.