Every Heart a Doorway by Seanan McGuire

Tied for first place in this poll is Every Heart a Doorway by Seanan McGuire.

Regarding location - Google will may say that the Hugh is closed, but it is not. We will meet inside the food court and there will be sign holders on the table with the book cover on it.

From Good Reads:
Eleanor West’s Home for Wayward Children

No Solicitations
No Visitors
No Quests

Children have always disappeared under the right conditions; slipping through the shadows under a bed or at the back of a wardrobe, tumbling down rabbit holes and into old wells, and emerging somewhere... else.

But magical lands have little need for used-up miracle children.

Nancy tumbled once, but now she’s back. The things she’s experienced... they change a person. The children under Miss West’s care understand all too well. And each of them is seeking a way back to their own fantasy world.

But Nancy’s arrival marks a change at the Home. There’s a darkness just around each corner, and when tragedy strikes, it’s up to Nancy and her new-found schoolmates to get to the heart of the matter.

No matter the cost.