Averno, a crater lake in southern Italy, was for the Romans the entrance to the underworld, both gateway and impassable barrier between the living and the dead. In Louise Gluck’s latest collection, Averno is the only source of heat and light in a world turned to icy winter. Ancient myth is reanimated in the desolation of Persephone’s laments for the lost warmth of earthly life. Both epic and intimate in scope, “Averno” explores the enduring drama of love and death.