Gus spots a story in the morning paper about a body found off the marina. As he and Ace head out to see if it is Nathan Israel, they run into Ace's grandson in the lobby. The young man thanks Gus for sending him a plane ticket, and Ace and Gus realize that Mike flew him in as a veiled threat. Ace tells the kid to stay in his suite no matter what, but doesn't want him to know he's in danger.
The Foray Stables owners nervously prepare for the Derby Day. Marcus worries about inviting his doctor to the race, suspicious of his motives, but Jerry sets him at ease. Renzo picks up his mother at the bus station and brings her to the track. Jerry shares his picks with the group and they lay down their bets-they're playing the Pick Four and betting big on their own horse and Pint of Plain both winning. Just before the race, Escalante introduces them all to Rosie and gives her some last minute advice
One of Mike's men photographs Ace leaving the building. The man meets with a hit man and shares the details of Ace's routine. At the morgue, Gus and Ace see Israel's body. Ace is devastated, knowing he put the young man in harm's way. As they drive away, Ace has Gus stop the car and calls Claire at the horse farm; the sound of her voice has a calming effect. Ace pays a visit to his parole officer and tells him about his "friend's" horse. As he leaves the building, Gus spots the hit man on a roof across the street and has Ace go back inside and leave from a different exit.
Later, Gus and Ace dine in a coffee shop and Gus spots Mike's man watching them. Ace stages a loud argument with Gus who makes a show of leaving the table to call the grandson while Ace heads to the restroom. In reality, Gus hides in the bathroom while Ace draws the hit man inside. Gus catches the hired gun off guard and, after a struggle, kills him. Mike's spotter sees Ace coming in from outside and, realizing something is very off, phones the dead hit man frantically. When he returns to his car, Mike's man is whisked away by one of Gus's men, who'd been lying in wait.
In the earlier race, Rosie rides Mon Gateau to victory as the horse's owners and their guests look on. Leon cheers her on from the sidelines and Jerry gives him a winning ticket for his part in getting the horse to this point. The Bug Boy is moving to Portland and already has three mounts lined up.
Gus and Ace arrive at the track and check on their horse. Physically he's fine, Escalante tells them, but the stable goat that usually accompanies him has gone missing. "Like everyone else, he has a routine," the trainer says, and Ace relates. At the Walking Ring, Mike approaches Ace and compliments him on his adaptability. Mike tries to intimidate Ace by letting him know he's been given a very long leash.
In the Western Derby, Escalante's Pint of Plain and Walter Smith's Getting'up Morning are the favorites for the winner's share of the race's million dollar purse. Coming down the stretch, Pint of Plain is slightly ahead, but Ronnie Jenkins pulls the old man's horse alongside him, riding stride for stride. It comes down to a photo finish, and Pint of Plain is declared the winner.
Ace's grandson shows up at the race, terrifying Gus and Ace that he is out in the open. Ace pulls him into the Winner's Circle as Mike, DiRossi and Cohen look down from a box above. Mike contemplates buying the track and tearing it down to build tract houses.
Walter speaks to Ronnie, and tells the veteran jockey he did everything right and shouldn't blame himself for losing. Later, the older trainer and Escalante praise each other and bemoan the "cockroaches" who'll come after their horses now.
At the hospital, Jo tells Escalante she lost the baby, and he comforts her. At Ace's suite, he reconnects with his grandson. And at the Oasis Motel, the members of the winning team celebrate their victory and their good fortune.