Teenagers fill the ER after a school-bus crash; Bailey treats a patient who was her high-school crush; Derek goes on a date with a fellow doctor; Thatcher enters the ER looking for Meredith.
George and Izzie test their romantic chemistry; Derek asks for more than a physical connection with Meredith; Mark develops a crush on a fellow surgeon; Callie finds her role as chief resident jeopardized.
As the holiday season passes, Miranda is visited by her father, who disapproves of her life choices; Mark and Lexie must cope with the arrival of a woman from his past; Thatcher questions the chief's recent behavior.
Addison takes a temporary leave from Seattle Grace and visits old friends in Los Angeles; Cristina reluctantly plans her wedding with help from Burke's mother (Diahann Carroll) and her own; Derek must perform surgery on Jane Doe.
Amelia and Koracick tackle a daunting surgery on Catherine; Richard urges Meredith to visit her father before his time is up.
