Liars' Room — Dan Poblocki

This spooky stand-alone from MG horror expert Dan Poblocki is perfect for fans of Katherine Arden and Victoria Schwab!
Simon is a liar. Stella and Alex know this about their new step-brother, so they aren't bothered by his stories about their new house. Wildwyck, a former schoolhouse for misbehaved boys, might have plenty of creaks and shadows, but the twins know that ghosts aren't real. But Simon is getting harder and harder to ignore, as his cries for attention become increasingly dangerous and difficult to explain.

Stella and Alex have to consider . . . could Simon actually be telling the truth? As they look for answers, they learn that the history of Wildwyck is more sinister than they could have imagined. And when a shocking truth is revealed, it's not clear who can be trusted anymore.

Will the three siblings be able to put aside their differences to save their family . . . before it's too late?