The sibling rivalry between Frasier and Niles reaches a fever pitch when they compare IQ scores.
Carrie thinks Mr. Big is keeping her a 'secret' while Miranda discovers a sex secret about her new boyfriend. Samantha has never been discreet with anyone she's ever slept with, and Charlotte divulges her past secret love affair with a Hasidic Jew.
The BAU travels to New York City to investigate a series of murders that appear to have been committed by a vigilante who is exacting revenge on other criminals who have been released by the justice system.
Danny works to discover the source of a deadly narcotic after three teenagers die from a drug overdose.
Holmes and Watson investigate a mass murder when a chef and his patrons are poisoned after dining on a tasting menu tainted with snake venom. Also, Detective Bell's crush on a work colleague makes Holmes realize his and Fiona's (Betty Gilpin) relationship is at an important crossroads.