When a janitor attacks a school coach, the SVU team connect his violent behaviour to a history of sexual abuse. They identify more victims of the same predator, including prisoner Reggie Rhodes on death row.
Danny persuades his brother-in-law to assist him take care of some mobsters he's become involved with. Elsewhere, Frank asks Erin to look into his old partner to see whether or not he is guilty of shooting someone at a strip club.
The team hope their stomachs are strong enough to handle an investigation into the death of a polo player. Meanwhile, McGarrett's mother makes an unexpected visit.
A Russian nuclear submarine disappears in American waters, putting Elizabeth in a tricky situation; Stevie ends things with her boyfriend.
Watson discovers an unsolved murder is connected to a rare prehistoric fossil when she reviews a cold case; Sherlock's responsibilities as a sobriety sponsor cross personal boundaries.