William learns that Lucian, one of his students at Durhnam University, hasn’t returned for three days. What’s more, the waitress Lucian had vowed to love throws herself from a bridge and dies. However, one of the university’s administrator assures William there’s nothing to worry about, but William disagrees and begins to investigate Lucian’s last movements.

Moriarty pretends to believe Blitz’s lie that he killed Thomas in self-defense and offers to cover up the crime.

With 48 minutes remaining before the train reaches the next station, Sherlock declares that William and he can find the murderer in time. Sherlock relies on the evidence at the scene, while William pursues a psychological profile of the killer.

Despite Sherlock recognizing that Irene is dealing with the Lord of Crime, he sees her off. Irene negotiates with the Lord of Crime in an abandoned church, but before she can turn over the papers, Sherlock arrives, and makes a deal to keep Irene safe.

Milverton blackmails Mary, exploiting her dalliance in antigovernment activities as a student. Sherlock decides to sneak into Milverton's estate to steal his evidence, but even that act was anticipated. Sherlock finds that he is not the only trespasser.

When William James Moriarty claims responsibility for being the Lord of Crime in all the papers, aristocratic condemnation and public anger falls upon the Moriartys. The final problem of the Moriarty Plan that William has concocted at long last begins.

William aims to complete his plan with his death, as Albert and the others each carry out their roles. Meanwhile, Sherlock deduces William's true reason for having him vanquish the Lord of Crime. Overlooking London, the pair face each other one last time.