Cassie Lenue comes to see Sherlock and Joan. She wants their help to solve a murder. The victim's name is Heather Foley, her former foster mother. They are both skeptical. They agree to look into the murder, but make Cassie stay with them for the duration of the investigation. Sherlock meets Heather's husband Judd. He thought Heather was having an affair. Heather was buying stolen baby formula as an informant for the New Jersey State Police, which may have why she was killed. She was part of a racketeering investigation. Heather's boss, Meredith Sagehorn, is a suspect in her death. Sherlock suspects Cassie is working for a drug gang to find out what the police know. Sherlock goes to check out Cassie's halfway house. Cassie tells Joan that Sherlock is her father. Cassie said Meredith didn't have Heather killed. Sherlock found out Cassie was researching unsolved murders. He said Cassie's target was them. Sherlock confronts Cassie. He thinks she's trying to find a way to connect to people. The New Jersey police are backing off. Joan and Marcus want to find other lieutenants in Meredith's organization. Sherlock comes up with a new theory. He thinks Heather was killed to stall the investigation. The state legislature was likely to eliminate formula subsidies, which would hurt supermarket sales. He suspects supermarket boss Mack Leehoven. Cassie breaks into Leehoven's home to blackmail him for $2 million not to tell what she knows. Cassie sneaks back into the townhouse but Sherlock catches her. She tells him she had set up a meeting to take Leehoven's money. State Police Detective Calabrissi was Leehoven's fixer who killed Heather. Sherlock found out Cassie's real name, but she doesn't want to know. He gives her an application to change her name.