Tracker eighteenth episode of its second season, titled “Collision” centered on a high-stakes investigation led by Justin Hartley as Colter Shaw, tasked with finding a missing former model named Riley Adams. The story unfolded in the small town of Willow Creek, Michigan, where a simple case quickly became a complex web of secrets involving a hidden pregnancy, obsessive behavior, and desperate crimes. The episode first aired on CBS on Sunday, April 27, 2025.
Episode Recap: The Mystery in Willow Creek
The episode “Collision” began with Riley Adams, a 26-year-old who had recently moved back to her hometown from New York, driving home from work. After being sideswiped by another vehicle, she disappeared. Her mother, Susanna Adams, hired Colter Shaw, offering a $15,000 reward for her safe return. Despite minimal initial evidence, Colter took the case and partnered with local Detective Katie Douglas.
The investigation revealed Riley was five months pregnant, with the father being Vincent Rourke, a married club owner from New York who had come to Michigan to see her. Early suspicion fell on Riley’s childhood friend and coworker, Cheryl Davies, whose obsessive behavior was documented in love letters. However, the situation escalated when Cheryl was found dead in her home, with a message written in blood staged to look like a murder-suicide. Colter deduced this was a cover-up, leading him to the real culprits: Tyler and Monica Harper.
The Harpers, a local couple who had suffered multiple miscarriages and could not adopt due to Tyler’s criminal record, had kidnapped Riley to take her unborn baby. Monica, a nurse with a history of impersonation, planned to raise the child as her own. In a tense final confrontation, Colter and Detective Douglas discovered a hidden room above the Harpers’ garage, where Monica was holding Riley at knifepoint. Colter negotiated with Monica, focusing on the safety of the baby, which led her to surrender. Riley was safely reunited with her mother.
Main Cast & Characters in “Collision”
This episode featured the show’s core team alongside several guest stars who drove the central mystery.
Justin Hartley as Colter Shaw
Justin Hartley leads the series as Colter Shaw, a survivalist and expert tracker who helps people for reward money. In “Collision,” his skills in observation and reading people were vital as he sorted through misleading clues and personal secrets in a tight-knit community. Hartley is also known for his role in This Is Us.
Annalisa Cochrane as Riley Adams
Annalisa Cochrane played Riley Adams, the missing woman at the heart of the episode. A former model and pageant winner, Riley’s hidden pregnancy and her decision to return home from New York set the entire plot in motion. Cochrane’s other acting credits include Cobra Kai and One of Us Is Lying.
Abby McEnany as Velma Bruin
Abby McEnany portrayed Velma Bruin, one of Colter’s handlers who connects him with new cases. In this episode, Velma was the one who first contacted Colter about Riley’s disappearance and the offered reward. McEnany is also known for the series Work in Progress.
Supporting Team: Tech and Legal Help
Colter’s remote support team played a key role in cracking the case from afar.
- Eric Graise played Bobby Exley, the tech expert who assists Colter with digital investigations. Bobby helped track phone records and obtain critical security footage.
- Fiona Rene returned as Reenie Greene, the attorney who provides legal research. She uncovered the Harpers’ troubled history with infertility and Monica’s false identity.
- Chris Lee played Randy, Bobby’s cousin and fellow hacker who assisted with research and added light-hearted commentary.
Guest Stars & Antagonists in Episode 18
The guest cast for “Collision” included the victim’s family, red herrings, and the true villains of the story.
The Harper Family: Monica and Tyler
The episode’s primary antagonists were a couple driven by tragic motives.
- Hayley McFarland played Monica Harper, a nurse whose desperation to have a child led her to commit kidnapping and murder. Her calm demeanor made her actions even more unsettling.
- Tom Stevens played Tyler Harper, Monica’s husband, who used his construction skills to build a hidden room and enabled his wife’s plan.
Riley’s Circle: Family and Friends
- Reagan Pasternak played Susanna Adams, Riley’s worried mother who hired Colter.
- Summer Lynn Gillespie played Cheryl Davies, Riley’s obsessive friend from work who became an unintended victim.
- Christopher Russell played Vincent Rourke, the father of Riley’s baby, who initially appeared as a suspect.
Local Law Enforcement
- Mercedes de la Zerda played Detective Katie Douglas, the local sheriff who partnered with Colter. Her knowledge of the town and its residents was crucial, though her initial assumptions sometimes needed correcting.
Additional Appearances
Other actors appearing in the episode included Guy Fauchon as a hotel manager, Sam Krochmal as a valet, Chris Pereira as Riley’s coworker Todd, and Jacob Insley as a deputy.
Behind the Scenes of “Collision”
The episode was directed by Joel Novoa. It was written by a team that included Dominique A. Holmes and Ryan O’Nan, with the story based on characters created by author Jeffery Deaver. The series “Tracker” itself is developed by Ben H. Winters.
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