u/Banana_Fartman_

"Deep within the labyrinthine archives of the ancient library______ a collection of manuscripts, the existence of which has been debated by scholars for centuries."

I thought the correct word would be "lies", but somehow I received a vague explanation that "lie" is the correct answer.

Is there some sort of lesser known grammar rule behind it?

Edit 2: Yep, it's "lies", I don't know what my tutor is smoking.