Willis continues to tend to Rox's medical needs; Leanne and Max's father go searching for Ariel; Noa and Mario realize their career choices will mean ending their relationship.
An extremely intelligent Navy coder -- employed by Brody's mom (Annie Potts) -- is put in danger when the heart intended for him is stolen.
Izzie's medical condition requires a difficult surgery; one of Owen's PTSD episodes causes Cristina to be injured.
Martin meets a homeless man who shares Jake's obsession with numbers; Teller (Danny Glover) visits Jake's board-and-care facility.