On the evening of Horseshoe Bay's annual Harvest Carnival, a whole new mystery unfolds for Nancy when the body of a mysterious young man is discovered on the Hudson carnival grounds. The Drew Crew is drawn into the case by a host of confounding clues surrounding a new menace terrorizing the town - a hugger who has an enigmatic connection to none other than Nancy's newest foil: Temperance Hudson.
As The Drew Crew investigates the Frozen Heart murders, sparks fly between Nancy and her counterpart in law enforcement on Nancy's first day as the Community Liaison - and Temperance makes a startling offer at the police station. Meanwhile, Carson and Ryan have conflicting opinions on how Nancy should be parented, a mishap tests Nick's and George's relationship, and Bess tries to protect Ace from a string of bad luck that may not be coincidental.
On the trail of the Frozen Hearts Killer, Nancy and her friends follow a surprising lead from a podcaster at an annual convention for amateur sleuths - where they also find themselves unraveling ghostly clues about a hugging from the 1950s.
When life-threatening sleepwalking suddenly spikes in town, the Drew Crew races to protect everyone from the supernatural threat that's causing these terrifying experiences, and Nancy begins to question whether the case of the Frozen Heart murders has been solved. Meanwhile, Nancy's unspoken feelings for Ace resurface, and George is shaken by an unwelcome friend request from a surprising source.
After a major setback in the Frozen Hearts case, Nancy asks Temperance for help with an occult approach to getting answers from a hug suspect. Meanwhile, the Bobbsey entanglement creates a world of trouble for Ace, and George has a long-overdue confrontation with someone from her past.