In the seventh episode of Tracker, Colter Shaw arrives in Chicago, Illinois, this time not on a paid mission but on a personal one. He joins his friend Bobby in searching for Sun Mai, a Vietnamese MMA fighter who has vanished without a trace. Days have passed since Sun's disappearance, and the last sighting of her was as she exited her gym through a back door leading into a dim alley.
Upon scrutinizing the scene, it becomes apparent that Sun's disappearance was not voluntary. Her phone lies discarded near some bins, a chilling clue that alerts the pair to her predicament. They turn to Dake, a fellow fighter at the gym who had a heated altercation with Sun on the night of her disappearance. Despite his intimidating demeanor and fiery temper, Dake seems genuinely surprised by their inquiries.
Art Arfano, the gym's owner, steps in to offer his insights. He reveals that Sun had been tense in the past few days due to her visa issues. She lives with her mother, Apple, both of whom are on the brink of deportation. This looming threat may have pushed Sun to take drastic action.
Colter doesn't discount the possibility that Sun may have been apprehended by federal immigration agents. Alongside Bobby, they visit Apple and learn about a lawyer named George Prine, whom Sun had been consulting. While searching through her laptop, Bobby stumbles upon evidence that suggests Sun held a grudge against George. It turns out that George, alias Marv Johnson, had cheated both Apple and Sun out of money, posing as an immigration expert.
Colter's visit to George's office alerts the conman and his accomplice. George, determined to get to the bottom of things, follows Colter with a gun. But Colter manages to overpower George and take control of the situation. After a tense confrontation, George reveals that he's in cahoots with a loan shark group. He sends his victims to this group to arrange for cash to cover his fees and purportedly secure visas. George confirms that it was this group who took Sun after he arranged a meeting between them. He also provides information about a van that the group often uses.
Meanwhile, Reenie discovers through her sources that Sun is not in detention. She promises Apple that she will do her best to help them renew their visas. With Bobby's assistance, Colter tracks down the van, which is abandoned in a desolate parking lot. The search for Sun Mai has led them to a dangerous and uncharted territory, and they are now more determined than ever to find her and unravel the mystery surrounding her disappearance.
Inside the shadowy confines, Colter stumbles upon sacks filled with cash and two men closing in on him. With quick wit, he cunningly deposits his phone in the van, calling on Bobby for rescue. Later, as Bobby and Reenie trade stories about Colter's grueling past, they delve into how he shuns talking about it, preferring to roam the world as a lone wolf. Bobby confesses that Colter had once saved his life from the clutches of the Russian mob during a disastrous online hacking incident.
Tracing his phone, the pair finds themselves outside a dingy, decrepit building. Despite Colter's instructions to wait in the car, Bobby stealthily follows him inside. Inside, Colter's eyes widen in horror as he witnesses Sun engaged in a brutal fight with another woman, while a bloodthirsty crowd cheers them on. It's an underground fighting ring, a den of iniquity where organizers profit from the fighters' miseries.
Finally, Colter manages to speak with Sun in private. She confesses that loan sharks have offered her a chance to repay her debts by participating in these grueling, illegal fights. It's an inhumane task, but one she must endure to clear her debts. Colter urges her to abandon this circuit and promises safety for both her and Apple. But as they prepare to flee, a gun-wielding man steps into their path. Bobby, who has sneaked up behind him, bravely distracts the thug, allowing Colter to take him down.
The final revelation shines a spotlight on the mastermind behind this sordid scheme: Art. Bobby and Colter are cornered by him and his henchmen. Art shows no remorse for forcing Sun and the other fighters to endure hellish ordeals for his own greedy profiteering. But in a stroke of inspiration, the trio works together as a team and succeeds in getting Art arrested.
With Reenie's legal prowess, Sun and her mother are given a chance at a U-visa, a special path tailored for victims of crime. Bobby and Sun seem to embark on a new relationship, while Colter once again hits the road, heading towards his next destination: Sioux Falls.
