Translation of "нежданного" in English

Отлично зная, что жена собиралась пойти в кино, муж, эта собака на сене, устроил так, что им пришлось остаться дома в ожидании некоего нежданного гостя.

Knowing very well that his wife wanted to go to a movie, the husband, who was a dog in the manger, cooked up a scheme whereby they had to stay at home waiting for a certain visitor who was not expected to come.