Mercenary Martin David, portrayed by Willem Dafoe, is enlisted by the military biotech company Red Leaf with a daunting mission: to travel to Tasmania to collect samples of the elusive Tasmanian tiger, which is believed to be extinct. Red Leaf aims not only to gather DNA but also intends to eliminate all remaining tigers to prevent other organizations from acquiring their genetic material. This high-stakes contract comes through a middleman, Jacek Koman, placing Martin under immense pressure as news of the tiger's existence could spread rapidly. With just a few weeks to accomplish this compelling task, Martin, known for his precision and discipline, embarks on his journey.
Arriving in Hobart, Martin adopts the guise of a university biologist and takes lodging with the Armstrong family. The household, consisting of Lucy, portrayed by Frances O'Connor, and her two children, Katie – played by Morgana Davies, and Jamie, faces constant challenges due to its deteriorating state, including erratic electricity and contaminated water supply. Despite his intent to stay at a local tavern, the unwelcoming community, which views him suspiciously as an environmentalist akin to Lucy's missing husband, Jarrah Armstrong, leaves him with no choice but to reside with the Armstrongs.
Lucy’s life has been thrown into disarray following Jarrah's mysterious disappearance. He was an environmentalist who had clashed with local loggers desperate for work, leading to speculation and gossip that swirls around the town. As Lucy copes with her grief, heavily sedated by medication, Martin feels compelled to assist with repairs around the house while also working on his mission. With an adeptness for survival, he ventures into the wild for extensive periods, consistently setting traps in hopes of spotting the elusive tiger. His meticulous mapping of trap locations showcases his skills as both a hunter and a survivor.
The tranquility of the bush is soon interrupted by distant gunshots, hinting at the presence of rival hunters or perhaps angry locals. Tension escalates when he returns to find his vehicle vandalized. In brief visits back to the Armstrong residence for supplies, Martin forms a bond with Lucy's children, particularly when he uncovers the truth about Lucy’s dependency on her medication, which is delivered by Jack Mindy, a character portrayed by Sam Neill. Recognizing the detrimental impact of her addiction, Martin takes action by temporarily seizing her medication.
During one of his treks through the forest, Martin makes a grim discovery: Jarrah’s skeletal remains, leading him to arrange for a respectful burial, all the while keeping this revelation from Lucy and the children. As he integrates into the Armstrong family dynamic, he learns more about the histories that intertwine them and the dangers of his undertaking. Martin uncovering a drawing from Jamie, depicting the tiger near a water source, gives him a pivotal clue on where to locate the animal.
However, the stakes rise significantly when Martin learns that the company he works for had originally hired Jarrah for this very mission, only for him to abandon it in favor of environmental advocacy. This complication deepens when Martin becomes embroiled in a life-threatening confrontation with a rival Red Leaf operative, sent to replace him. Employing his cunning, Martin turns the tables, leading his adversary to a trap that results in a deadly altercation.
Upon returning to the Armstrong residence, Martin discovers devastation— the house is engulfed in flames, and Lucy and Katie tragically did not survive. With Jamie taken into custody by the authorities, Martin feels a renewed sense of purpose. Determined to put an end to Red Leaf’s ambitions, he finally spots the Tasmanian tiger and, though reluctant, he fulfills his grim responsibility by shooting it before ensuring its secret remains buried.
In the aftermath, Martin informs Red Leaf that the creature they sought is "gone forever." The film closes with Martin making his way to a local school, where he finds Jamie sitting alone. Their heartfelt reunion offers a glimmer of hope amid the wreckage of their respective lives.
