The day has arrived that Cristina leaves for Zurich, but a possible act of terrorism delays her departure. Before she can get to the mall to buy a European phone charger, an explosion at the mall sends multiple injured victims to the Grey Sloan Memorial Hospital. Leah comes to the ER when she hears about the explosion, but leaves with no goodbyes when she sees every patient had been treated. April receives a pep talk from Catherine Avery, her mother-in-law, when she starts to fear raising a baby in a world that is so dangerous. Cristina, looking for closure, can't leave the hospital until she and Meredith dance it out one last time. Shane demands that he take control of his education and leaves to work under Cristina in Zurich. Meredith tells Derek that she can't leave Seattle, the place where she grew up and made her life; she's not going to Washington, D.C., despite what Derek says. Callie and Arizona consider having a surrogate mother carry their future baby after treating a surrogate who was burned by the explosion. Bailey is nominated for a position on the board by Webber due to Cristina's departure; however, Cristina left Karev her shares of the hospital and her board position. Webber connects with Dr. Pierce, the new head of cardio, and finds out that her birth mother was Ellis Grey.