Susan Merson

Derek looks for the perfect way to propose to Meredith; Lexie wants Mark to go public with their relationship; Bailey considers taking her medical career in a new direction.

Derek and Addison face off as they try to save a pregnant patient's life; a surgeon botches a standard procedure; Bailey is shocked by the chief's recommendation letter.

Grissom and the team battle the flu while investigating the deaths of several key witnesses in a grand jury case involving a dangerous Las Vegas gang.

Ally and John take the case of a wrongful death that Richard thinks will profit the firm; Ally and Glenn discuss their feelings for each other.

When the hijackers of a truck carrying radioactive material threaten to detonate a dirty bomb in Los Angeles, Don and the team race against time to thwart the plot.

When Monk undergoes hypnosis therapy, he reverts to his 9-year-old personality.