S3·E4 The Red Queen

This is a wonderfully crafted episode, that is centered entirely around Dr. Collin in casualty. He is the sole doctor available, aside from scant help from Liz Reid, and treats several patients under difficult conditions, including a heart attack victim, a man who has a potentially dangerous cord compression, and a man suffering from a drugs overdose.

His main problem is that he is unable to refer patients due to a lack of beds. In the end he manages to refer the most urgent of the patients, and find time to go to the toilet!