The Pied Piper of Hamelin(1980)

In 1376, the city of Hamelin is freed from a plague of hungry rats by a mysterious Piper who plays a tune and leads the vermin on a mery dance out of town and straight in to the river. But the greedy city Governers refuse to pay their agreed fee, so the Piper wreaks a terible revenge. He plays his pipe once more, only this time he leads all the children of Hamelin away to a magical mountain portal, from which they never return...