Simultaneous, Eric Heisserer (Review by Lara Ferguson)

Eric Heisserer’s Simultaneous is a mind-bending speculative thriller that examines the fragile boundaries between time, identity, and causality. The story’s foundation is rooted in soul-sharing across multiple bodies and timelines and raises intriguing questions about the consequences of manipulating history—intentionally or not. At the heart of the story is Grant Lukather, a Homeland Security agent in Predictive Analytics, and Sarah Newcomb, a therapist whose past-life hypnosis uncovers a phenomenon that challenges linear time. Sarah has a patient, Marigold, whose consciousness overlaps with another living person, Brian, who is a police officer, deeply affected by an old case involving a serial killer. As the trio races to stop this serial killer, whose actions ripple across realities, they confront a chilling possibility: that changing one timeline could fracture others, with unintended and irreversible consequences. Heisserer doesn’t rely on traditional time machines or paradoxes. Instead, he explores time travel through consciousness and reincarnation, creating a layered narrative where past, present, and future coexist. This approach allows for a fresh take on the genre, but it also introduces thorny dilemmas. If a soul can influence multiple lives simultaneously, what happens when one version makes a choice that alters another’s fate? Can justice be served without destabilizing reality itself? Simultaneous offers a high level of action and thrill which maintains the readers interest, but the novel’s tension lies not just in the chase, but also in the philosophical stakes requiring the reader to contemplate deeper ideas. Heisserer teases out the dangers of retroactive interference—how even well-intentioned actions can unravel the fabric of identity and memory. The characters grapple with whether they’re solving crimes or rewriting destinies, and the ambiguity is part of the thrill. While the pacing occasionally rushes past deeper explorations of these ideas, Simultaneous draws the reader into the action while remaining a compelling meditation on the ethics of intervention. It’s a story that asks: if you could change history, should you? And more importantly, who gets to decide?