The previous episode of "Grey's Anatomy" confirmed Meredith's suspicion that back in D.C., Derek cheated on her. Indeed, the surgeon locked lips with his smart and good-looking employee Renee but recoiled once he realized that what they were doing was wide off the mark. 

While the couple sorts things out, Derek has one more thing to settle in his homecoming, and that is to give Amelia a showdown to determine who the boss really is. In the promo for the upcoming episode titled "When I Grow Up," Derek sets things aside to let his younger sister lead. However, the neurosurgeon is not easily swayed by her big brother's actions and she herself knows that her being the boss is very unlikely.

While on the subject, the next installment will also show Amelia dealing with the fact that she has feelings for Owen. 

Also in episode 18, the doctors of Grey Sloan Memorial Hospital tend two injured cops. This happens, unfortunately, on the same day kids are having a school field trip in the same hospital. As expected, the group of touring youngsters witness how the wounded police officers are rushed to the emergency room. So apart from treating them, the doctors have to deal with reaction of the kids.  

During the fiasco, Stephanie gives her full attention to the chaperones while Callie is the one to operate on the leg of the police captain who is injured in action. 

Episode 18 of "Grey's Anatomy" season 11 titled "When I Grow Up" will be aired on April 2.