On the island of Sri Lanka, at a colonial mansion between the forest and the paddy fields, a caretaker arrives with four children in tow after pledging to keep them safe. When violent thugs storm the house demanding that Ushu repay his debt, young Jasmit and the other children hide in an upstairs bathroom where a running tap opens a gateway to escape. But the Dry House is not the only force at work in the place where the forest and the estate meet - something else stirs in the trees, something ancient, something that demands retribution.

The Sap Mother bides her time, watching and learning from the house's inhabitants. She burrows beneath the foundations of the Dry House, hungry for atonement. Pulled between these warring powers, Jasmit must choose between saving those trapped in the mansion's bulging stomachs and preparing the house for when the Mother emerges again.