If, Then

The lives of three neighboring families in Clearing, Ore., become inexorably entwined in Day’s captivating debut novel of parallel worlds. Dr. Ginny McDonnell, a surgeon, feels disconnected from her son, Noah, and her husband, Mark, a behavioral ecologist convinced that nearby Broken Mountain, a volcano, isn’t quite as dormant as many believe. Realtor Samara Mehta is still reeling from her mother’s death on the operating table and blames the surgeon, Ginny. Cass Stuart is taking a break from earning her PhD in metaphysics to care for her baby girl but longs to continue her research on the theory of everything and the possibility of a multiverse. Cass, Ginny, and Mark start to glimpse different versions of themselves and Samara of her mother, preceded by a bad taste and a trembling under their feet, while Broken Mountain awakens nearby. Often, Day seamlessly slips readers in and out of realities with little warning, and the scenes in which characters observe and, at times, interact with, their alternate realities are intimate, eerie, and startling, such as Mark’s encounters with the wild, disheveled man he dubs “Other Mark.” Effortlessly meshing the dreamlike and the realistic, Day’s well-crafted mix of literary and speculative fiction is an enthralling meditation on the interconnectedness of all things. (Mar.)