S2, E19: A hacker demanding a ransom payment shuts down the hospital computer system, forcing the doctors to diagnose patients without the aid of technology. A stressed Goodwin (S. Epatha Merkerson) struggles to keep the hospital afloat when an unexpected visit from her ex-husband Bert (guest star Greg Alan Williams) and his new girlfriend (guest star Garcelle Beauvais) make matters worse. Making use of his former navy experience, Dr. Choi (Brian Tee) and Noah (guest star Roland Buck III) have to locate a bullet inside a patient with a gunshot wound. Meanwhile, Sarah (Rachel DiPillo) feels Dr. Charles (Oliver Platt) may be trying to push her out and Robin's (Mekia Cox) unusual behavior worries Dr. Rhodes (Colin Donnell). Marlyne Barrett, Yaya DaCosta, Nick Gehlfuss and Torrey DeVitto star.