George struggles with his guilt after admitting he loves Izzie, while Callie, as Chief Resident, is overwhelmed by her duties and her suspicions that George is cheating.
Meredith's half-sister, Lexie, attempts to bond with Meredith, who remains resistant to having a relationship with her. [S4E2] Love/Addiction
The residents and interns treat victims of a massive apartment fire caused by a meth lab explosion. Alex Karev deals with a particularly difficult case involving a baby who suffered a stroke due to the meth lab environment. George struggles with his guilt after admitting he