In the fourth season, Tony and Christopher stake out the retirement party of Detective Lieutenant Barry Haydu, the man who murdered Christopher's father. New York underboss Johnny Sack becomes enraged after learning Ralph Cifaretto made an inappropriate joke about his wife's weight and tries to have him clipped. Tony and Ralph invest in a race horse named Pie-O-My, who wins several races and makes them both a great deal of money. However, when Ralph's 12-year old son Justin is severely injured when an arrow plunges into his chest, Tony comes to believe Ralph burned Pie-O-My in a stable fire to collect $200,000 in insurance money. Uncle Junior goes to trial.Janice pursues a romantic relationship with Bobby Baccalieri. Christopher's addiction to heroin deepens, prompting his associates and family to organize an intervention. Adriana befriends a woman who is an undercover FBI agent. When the friendship ends, the woman reveals herself as an FBI agent and tells Adriana the only way to stay out of prison is to become a informant. Carmela, whose relationship with Tony is tense due to financial worries and Tony's infidelities, develops a mutual infatuation with Furio Giunta.