When famed neurosurgeon Dr. Ginsberg and her team pay a visit to St. Ambrose to save the life of Kayla, Addison is shocked to see Amelia Shepherd - Derek's younger sister on the team. But Amelia's presence causes strife between Addison, Sam and Pete when she claims she can save Kayla's life after Dr. Ginsberg declares nothing can be done. Meanwhile Charlotte seeks from Cooper's wit