On a full moon Saturday night, the ER is filled with patients who are especially strange. With Dr. Mark Greene (ANTHONY EDWARDS) still depressed due the loss of a pregnant woman (in a previous episode), Dr. Susan Lewis (SHERRY STRINGFIELD) runs the ER single-handedly.

Meanwhile, Dr. Douglas Ross (GEORGE CLOONEY) goes out on a date with Diane Leeds (LISA ZANE), and Dr. Peter Benton (ERIQ LA SALLE) hovers around his sick mother (BEAH RICHARDS). With the help of John Carter (NOAH WYLE) and Deb Chen (MING-NA WEN), Dr. Lewis saves an 18-year-old man hit by a car. While in the ER, the driver who hit him has a heart attack, and Carter gets a rare opportunity to do heart massage. Carter also treats a pregnant astrologer (KIMMY ROBERTSON), who insists on predicting Carter's future.

Dr. Lewis is so competent that she greatly impresses Dr. Willie Swift (recurring role - MICHAEL IRONSIDE - "Top Gun"), the new chairman of the ER. Dr. Greene, however, makes a terrible impression on Swift. Finally, Dr. Taglieri (RICK ROSSOVICH) gets specific about his wedding plans with his fiancie, Nurse Hathaway (JULIANNA MARGULIES).