A real estate agent showing a brownstone to a client discovers the strangled body of the owner, Donna Brooks, age 70, lying alongside a man of the same age. The man, Richard Sutton, apparently suffered a heart attack. But Elliot and Olivia ponder whether he suffered the heart attack after finding Donna dead, or after having strangled her himself. Donna had an active social life, and Richard turns out to be one of the men whom she dated. However, while he might have been dating Donna for her money, Richard was not her killer. Donna was a rigorous exerciser, that and the fact that she liked to work out with all of the windows open sped up the rigor mortis in her body, thus making her time of death in the early morning, rather than late at night, as M.E. Warner had originally stated.

Going back to the drawing board, Olivia and Elliot seek the help of Dr. Huang, who uses the FBI's resources to determine that the ligature mark on Donna's neck came from a rope used in rock climbing. Using the VICAP database, Huang finds two other cases where elderly women were strangled to death by using the same type of rope. Like Donna, the other victims were wealthy, and they also shared one other factor: they were all suffering from a terminal disease when they were killed. Olivia and Elliot find out that all three women used the same in-home health care provider, a company called RDH. When they check out the company, it is revealed that all three murdered women shared the same male nurse, a man named Gary Devaal. However, just when the detectives think they have a grasp on their suspect, they soon realize that they're up against someone who is far more insidious and deadly than they had originally thought.

"Bound" is a great mystery that just gets more fascinating as each layer is peeled away. Everyone gives a great performance here, including B.D. Wong as Dr. George Huang, whose much-needed persistence that Elliot and Olivia not accept the obvious turns out to be very sound advice. Diane Neal also shines as ADA Casey Novak, especially in a funny scene where she finds herself unexpectedly outnumbered by a group of judges. And the person playing the perp is simply superb. I don't want to tell you who he/she is, for fear of giving away the great twist. But this culprit is indeed a very sick, devious puppy, and the extreme lengths to which Elliot and Olivia go through to ensnare the perp is riveting to watch. Mariska Hargitay once again proves her acting chops in her final confrontation with the prime suspect, a scene with a disturbing final line--spoken ever so casually by the killer--that sends chills down the spine.