The Maiden of the Woods: An 11th Level Adventure for 5th Edition

Long ago, the druids of the Thornwood enacted a ritual designed to protect it from interlopers and outsiders. This old, powerful magic gave life to the trees when danger reared its ugly head, allowing them to defend themselves should the druids be overwhelmed or unable to assist. Centuries passed, and the druids slowly passed on, one by one, until none who remembered the ritual remained. The forest remained silent, however, as no real threat ever came to fruition.

Then, one day, the local village decided to send their lumberjacks into the Thornwood, something they'd long considered but never done. The men began to slice down tree after tree, relishing in their finds as the hearty wood would make for excellent houses and defenses. Unbeknownst to them, these acts were enough to trigger the forest's response. That night, living plants, slowly crept into the village and stole away one child for each tree cut down. When the morning came, not a single child remained within the village's walls. Heartbroken and confused, the parents of the missing children put out a call for adventurers to find their children and return them to their homes.