The basement of Emergency Department, and the rest of the hospital, is the network of underground passages used for storage or emergency exit purposes. In 2011, Lenny and Frank came across a fire which had started in the basement as a result of a Christmas tree placed near a plug socket. The fire quickly spread and engulfed the ED.
In 2016, Connie was taken hostage by a convicted murderer into the basement. They reached the basement but his leg infection opened soon after and he was readmitted to the ED where he later died.