Breaking into the Mutant Control Agency's headquarters to destroy the registration files on mutants, the X-Men lose two of their members against the Sentinels, but eventually gain another.

Duffy goes for tests and has to be admitted for a biopsy. Julian's paranoid about his relationship with Sandra turning into local gossip. A man collapses during a Jewish ceremony and finds himself in Casualty but fate deals a cruel blow when his wife collapses and dies. Rob treats a man with suspected pneumonia and prescribes penicillin but he is unaware the man's allergic to the drug. A student on a field trip decides that he's fed up with life and takes an overdose. A clinical error involving Sandra has far-reaching consequences for the department. Norma is under great strain, as the condition of her mother takes a turn for the worse.