Outrun the Night by Marie Wilkens

Penelope Geller and her brothers inherit their grandparents’ property after their parents’ death. They discover a fully-equipped bomb shelter, which becomes their only refuge in a post-apocalyptic world. As they navigate a world without power or communication, tensions rise and secrets are revealed. In this gripping EMP thriller, Penelope and her siblings fight to survive and unravel the mystery behind their inheritance in a dangerous new world.