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.

Sherlock and John, searching for the true criminal who killed Count Drebber, set a trap for the criminal using the wedding ring they found at the murder scene. Sherlock is able to deduce who the real killer is, who offers Sherlock a strange deal.