A 16-year-old girl named Hannah O'Flaherty discovers a secret portal in the basement of O'Keffee's Boarding School in Galway, Ireland, which unexpectedly transports her to Perth, Australia. There, she meets Brett Miller, a cleaner who introduces himself as Craig, his stepfather, and Wayne, his step-brother, who live with his recently remarried mother Jackie.

A long-buried secret is exposed when a sudden cellar explosion at O'Keefe's u...