Thaddeus Rigg is an expert geological surveyor whose sanctuary is the "Obsidian Expanse," a massive, completely open, and treeless active volcanic wasteland. His latest job seems routine: guide a wealthy tourist across the jagged, miles-wide open lava fields to photograph an active surface magma flow. But in the middle of the unforgiving, razor-sharp plain with no walls and absolutely nowhere to hide, the tourist draws a silenced pistol.

Thaddeus is left stranded and weaponless, discovering a horrifying truth. His client is a specialized forensic cleaner hired by an international cartel to dispose of high-profile bodies by throwing them directly into the untraceable magma vents. Thaddeus was marked for death because his meticulous geological maps accidentally charted the cartel's secret dumping coordinates.

But the killer doesn't give chase on foot. Armed with specialized drones and a heat-shielded tactical rover, the assassin begins herding Thaddeus across the open expanse directly into lethal topographical traps. Thaddeus must evade invisible, suffocating lakes of heavy Carbon Dioxide gas-the deadly Mazuku-and outrun massive, slow-moving clouds of hydrochloric Laze triggered by the killer's explosives. Discovering the assassin plans to use the heat-resistant titanium implants of his victims to map pressure tubes and trigger a catastrophic eruption, Thaddeus must fight back. Exhausted, his boots literally melting to the scorching rock, Thaddeus must weaponize his knowledge of the earth, risking a devastating, instantaneous phreatic explosion to survive the limitless volcanic wasteland-or be swallowed by the liquid fire below.