Sherlock is called in to investigate when a supposedly uncrackable bank vault called "The Leviathan" is breached. Meanwhile, Joan is pleasantly surprised when Sherlock meets her family and defends her choice to become a sober companion.
Alicia and Will go toe-to-toe with his ex during a court-ordered mediation, while Eli and Diane clash over the best way to handle a dairy company's PR disaster.
McCall becomes ensnared in a deadly battle between rival rap crews when she is hired by the wife of a famous rapper, Dilemma (Rick Ross), to prove the musician is innocent of murdering a fellow artist.
