In the perilous Mortmain Mountains, Klaus and Violet Baudelaire meet another well-read person, who helps them try to rescue Sunny from the villainous Count Olaf and his henchmen as they all near "the last safe place."

After the sudden death of their parents, the three Baudelaire children must depend on each other and their wits when it turns out that the distant relative who is appointed their guardian is determined to use any means necessary to get their fortune.