Steve goes to visit his father's grave on the fourth anniversary of his death and meets a woman named Ellie Clayton. Her father was killed and his father investigated and stayed in her life to check in with her. She's now a Deputy Prosecutor.
Everyone is helping Jerry move out. He sneaks away and Chin catches him listening to the people at the bookstore, tells him for the third time to back off.
Steve asks Chin if he remembers the case, he remembers one suspect was a homeless man named Burrows who had an alibi and disappeared. Realizing how much the case meant to his dad, he decides to reopen it and try to solve it.
Flashback: A man walks into the bar and shoots Ellie's dad. It doesn't look like a robbery. Steve tells Ellie he has a lead but not to get her hopes up.
Back at the precinct, the team locates the homeless man, who admits he hid a box he stole from near the crime scene. Steve concludes that the murder was a hit.
Steve asks Ellie if she remembers any strange behavior and she recalls her father arguing with a young man named Jordan. He's in jail now, Chin and Steve visit him. He was selling meth and Paul was trying to help him get out. It was hard because his mom was a junkie in debt to a dealer named Sykes. But he didn't commit the murder.
Steve calls in to check in on Danny, who is out of town with his family in the wake of his brother's death.
Flashback: Chin remembers John going to Ellie's home on Christmas day and bringing her a present.
Steve finds Ellie at the bar, which she's never had the heart to sell. He shows her a picture of the membership to an underground gambling club and tells her that her father's murder could have been connected to that. But she knows for a fact that he quit his gambling habit before she was ever born. Steve asks to exhume her father's body for more evidence.
Jerry sends Kamekona's cousin to the bookstore to get the book back, but he's told it's already sold.
The team gets more evidence that Ellie's father might have been a card shark who got mixed up with a gang. They match the gun to another shooting and connect it to a man named Malua. They find him, but he swears he didn't pull the trigger. It was his friend Sykes.
They ask Jordan for help to catch Sykes. They need evidence so they send him undercover claiming to be looking for work and get Sykes to admit to the murder on tape. But Jordan loses it and beats on Sykes and gets himself shot, causing the team to have to take out Sykes.
Jerry comes home to find the owner of the bookstore waiting for him and before he can say much a bag is thrown over his head and he's taken away.