Entanglements - Patricia Mason - Bog

Accidentally opening a vortex sucks! Fifteen-year-old KIZZY TAYLOR is just hoping for an evening of fun when she joins her friends in a spelunking expedition through an under-city tunnel. But fun turns bizarre when Kizzy accidentally opens a vortex and her stepsister is swept through to an evil alternate dimension. The only way to rescue her stepsister is to reopen the vortex and go in after her. But will Kizzy be able to return home?