Derek fails to follow through on a promise he made to Callie.
Arizona has a particularly bad day that worsens when she advises one of Callie's patients on a potential double amputation. Watch www xrysois se Greys Anatomy S10E15
Following a new non-fraternization policy, the hospital deals with the fallout, resulting in HR meetings and the suspension of one doctor. Derek fails to follow through on a promise he made to Callie