Carter misses his pregnant girlfriend who has returned to Africa. A family of four is rushed to the emergency room after suffering carbon monoxide poisoning from their faulty furnace--forcing the claustrophobic Neela to accompany a newborn baby into an extremely uncomfortable hyperbaric chamber. Meanwhile, Lewis is upbeat about her future with Chuck, while Sam has reason to ponder her relationship with Kovac. In addition, Lewis and Abby treat a maniacal man who's covered in blood, while Weaver counsels a mother whose young son tests positive for leukemia. Amid the chaos, Chen returns from China with her sick father in tow.