- "You have to hold on tight when danger drives you to the brink!"
- — Tagline, from the front cover
Pure Evil is the 97th book in the The Hardy Boys Casefiles series.
Callie's uncle Adam makes maple syrup in New Hampshire, and she's invited Frank and Joe to join her there for spring break. The idea is to go cross-country skiing -- a plan that quickly goes sour. Someone has deliberately tainted the crop, and if the Hardys don't catch the culprit, Uncle Adam will soon be tapped out.
But the threat to Uncle Adam's business is only the beginning. A gang has targeted other farmers in the area, and they've added two new names to their list: Frank and Joe Hardy. The boys are in the thick of it, facing bomb-throwing saboteurs and chain saw-wielding thugs in an all-out battle to save reputations...and save lives!