I read this book in the 1970’s. It’s a dystopian future where teens are trapped on an open staircase. They arrive separately and meet each other there. They must do certain actions in order to receive food.
Stump the Bookseller
New format, same book stumper solving.
This is definitely House of Stairs by William Sleator. You can find a detailed description of the plot here: https://en.wikipedia.org/wiki/House_of_Stairs_(Sleator_novel)
That’s it! The cover and description bring on more of the disturbing feelings I’ve always had about that book. Thank you!