Sephie assumes her principal's disappearance has something to do with the paranormal. In her town, it's not unusual for departed souls to hang out atop cemetery gates. But when her best friend Rori also vanishes, Sephie sets out to discover the real culprit - a time tunnel whose ground zero is her school. Sephie and her buddies make the intergalactic jump to find Rori. Contrary to all advice, Sephie secretly plots to loop back one year and save her mother, whose death was her fault - or so she thinks.

But changing the past isn't easy. Rori gets locked up in a 1942 asylum, while Sephie lands in 1915, held prisoner by two crazed astrophysicists. The school's exposure to a fourteenth-century strain of the Black Death makes a mess of things, too. Ultimately, Sephie faces an impossible choice. Should she risk a return trip through the weakening wormhole? Or chance dissipating into stardust in a quest to save her mom? It's a heart-wrenching choice since she's finally dating the boy of her dreams.