Christine's date with playwright Josh Richards goes wrong when she interrupts it to arrest a mugger. The next day Cagney & Lacey start an investigation into the identity of a deaf baby who was left behind in a hospital. What was unusual was that the mother paid all the bills before abandoning the child. Mary Beth offers to look after the little girl while they search for her mother. Harvey doesn't mind that much, the boys are disappointed that their mother brought a baby rather than a game computer.
At their next date Josh mentions to Christine that he finds her job depressing and grim. The detectives trace the baby's clothes to a rich couple living in Park Avenue. The couple's lawyer explains that they bought the baby from a baby broker, and as the baby had a 'defect' they returned it. Samuels tells the detectives that there's little they can do against the baby broker unless they can trace the baby's biological parents. The DA suggests that Cagney and Isbecki set a trap, as they are both blond. Blond babies with blue eyes are highly sought after.
Josh and Christine have lunch with some showbusiness friends of Josh. Christine can hardly hide her disgust with the other couple's superficial concerns. Afterwards she has a fight with Josh who accuses her of not being able to leave her job behind. Meanwhile Mary Beth has become so attached to the baby that she has given it a name: Jeannie. She tries to convince Harvey to adopt the child. (Originally they just wanted to find out whether they were ready for a third child of their own.) Harvey warns her that the dead child will need special attention.
Cagney and Isbecki's trap works. A clerk at social services puts them into contact with Jarvis, the baby broker. They can tape him while he makes them an offer. Through his files they find the baby's real mother. Cagney is so relieved that she has a drink with Isbecki. After her break-up with Josh, she practically offers herself to Isbecki.. Luckily, Isbecki is too much of a gentleman to take her offer.
Mary Beth meets Mrs Jessup, the baby's mother. Mrs Jessup wants the child back, and she's sure any court will take her side. Shortly afterwards someone from Social Services comes to Mary Beth's home to collect the child that will have to go in foster care as long as the trial goes on. Mary Beth tries to hide her great disappointment.