The hospital is hit with an unprecedented crisis; Meredith and Cristina's surgical skills are put to the test.
The team suspects that a man who made his money donating sperm was killed by a recipient who learned his records were inaccurate; Brennan enters a feud with a fellow author (Nora Dunn).
When a prominent astrophysicist is found dead in her car, Castle is led to theorize her death was the result of an alien abduction.
An accidental overdose brings Drs. Greene and Corday's baby into the emergency room, gripping the parents with fear.
Earl studies to get his GED after being rejected for a credit card.
