A psychotic patient vows to punish the medical staff and steals an army tank, grinding his way across Chicago towards the hospital. Meanwhile, Kovac is startled at the lack of concern among some 13-year-olds who are diagnosed with a sexually transmitted disease. Sam is jealous of Kovac's visiting French friend, Gillian (Simone-Elise Girard), and ponders the odd relationship between a concerned teenaged girl and her sick father who is in full cardiac arrest. One of the emergency room staffers suffers a heart attack. And Corday becomes enchanted with a charming fellow surgeon.