A woman hires Sherlock to find evidence against her husband who she believes is cheating on her. Sherlock agrees out of boredom.
Joan joins him at Dorchester Reid, the law firm where Steven works. However, they claim Steven was let go six months ago. Sherlock calls the number given to him by Steven's wife. A woman answers, claiming to be Steven's secretary.
The pretend secretary admits that Steven paid her to answer the phone and act as though he still worked there. Sherlock and Joan track down his new office.
Sherlock breaks into the empty office, SMH, and spies brain matter. The ME confirms it belonged to Steven.
Joan cooks dinner for Andrew. His father is in town and wants to have dinner with both of them. Joan agrees but seems uneasy.
Sherlock is calling SMH's client list and they all have reason to kill Steven.
Steven was a debt collector. Gregson tracks down one of his employees who has a record. Steven apparently tried to collect a debt in person. Afterwards, he came back and let go of everyone.
Sherlock tells Joan that Andrew is a placeholder, which is why she is so stressed about meeting his father.
They visit Owen Downey who was the last person Steven met with in person. However, they discover Steven had become friends with him and planned to forgive his loan.
Sherlock surmises it may not have been debt collecting that got him killed but being a debt forgiver.
Sherlock identifies the investors in SMH who would have been angry that Steven planned to forgive all the debts. But Steven had earned enough to pay back his investors, so they had no motive to kill him.
Now Sherlock believes that someone wanted Owen to remain in debt and killed Steven before he could forgive Owen's debt. Owen's property sits in the middle of a planned ski resort by Stern Investments and he was the last holdout.
Sherlock and Joan interrupt a meeting at Stern Investments and Sherlock accuses one of them of being a murderer. After looking them over, Sherlock apologizes. He doesn't believe it was any of them, but he does know who the killer is.
Stern Investments is represented by Dorchester Reid. The attorney, Colman Brown, would earn millions if the ski resort is built. When Steven had a change of heart, Brown killed him.
Joan meets with Andrew at a coffee house to breakup. Before they do, he starts gasping for air and collapses. Joan begins administering CPR.