The Building That Wasn't

When Everly Tertium encounters a strange man in the park claiming to be her grandfather, she is invited to visit a mysterious apartment building. There, she finds herself in a constant state of déjà vu, impossibly certain that she's already lived through these moments, already been introduced to these people, and already visited all of these rooms and floors. So why does she have no idea what's happening to her?
The longer she stays in the building, the more Everly becomes convinced there is more going on than meets the eye. Something is off, time seems to pass differently, and the people living there seem trapped. Slowly, Everly begins to wonder if she is trapped too. But would she even want to leave, if she could?
For readers who enjoy Vicious by V. E. Schwab, This is How You Lose the Time War by Amal El-Mohtar and Max Gladstone, and The Paradox Hotel by Rob Hart.