A dangerous plague appears to be spreading throughout the world. Frank learns that he has been vaccinated for the disease. His wife and child, however, have not.

Sabrina must renounce one of the two things she holds most dear in this exciting season finale. The teen's dreadful dilemma develops when she must decide whether to date Harvey or new love Dashiell. She needs advice, but her loved ones are busy celebrating Mother's Day - leaving lonely Sabrina longing for her mom's guidance. Rules prohibit the unlicensed witch from seeing her mortal mother until she's certified, so Sabrina writes her a letter instead. Unfortunately, all contact is forbidden, so the Witches' Council hands down a devastating decree: Sabrina must choose between her magic and her mom and between Harvey and Dashiell. Meanwhile, Salem's mother is also coming to visit and he hasn't told her he's spending the next hundred years as a cat.