Natural History

S2 E3: Dr. Manning (Torrey DeVitto) and fourth-year medical student Jeff Clarke (guest star Jeff Hephner) are forced to figure out a mystery illness when an Indonesian man who doesn't speak English arrives at the hospital in dire straights. Maggie (Marlyne Barrett) takes Dr. Halstead (Nick Gehlfuss) to her family reunion where he meets her sibling Denise (guest star Alexandra Grey) and uncovers deep-rooted family secrets. Meanwhile, Dr. Rhodes (Colin Donnell) takes on a complicated heart surgery without consulting Dr. Latham (guest star Ato Essandoh) and Dr. Reese (Rachel DiPillo) and Dr. Charles (Oliver Platt) encounter a woman experiencing an unusual pregnancy.