An elderly patient admitted into the E.R. for a heart condition sees a familiar face, a long lost love who happens to be in the E.R. as well for a fractured arm, and the staff find themselves caught up in their love story. Meanwhile, Karev treats a troubled teenage patient whose parents brought her in for schizophrenia, and Meredith can't help but tell Cristina about her suspicions of Owen -- which inevitably messes with Cristina's head.

The hospital is hit with an unprecedented crisis; Meredith and Cristina's surgical skills are put to the test.