Young siblings Dan and Helen must protect their new friend, a strange blue alien boy they name Peep-Peep, from the terrifying evil alien known only as The Thin (Space) Man, who's after him.

In the third and final installment of Not Alone, a persistent mother tries to convince the principal of a prestigious middle school to admit her daughter, but his elitism and reluctance to engage with her goes beyond what might be expected. As the conversation grows increasingly uncomfortable, the mother is forced to confront a horrifying truth. Desperation becomes grief, and her "daughter" has become something else entirely.