The boys drove up Blackpoot Pass towards their campsite. "Our trailer's really well-hidden," said Chet. "You cant even see it from here." "I'll say!" said Joe. "Someone's stolen it!". Frank and Joe found tyre tracks leading up the pass. Beneath a sheer cliff the trailer stood, abandoned. They approached cautiously - suddenly a shower of pebbles hit them, followed by the rumble of great boulders falling from the cliff directly above them..Forged credit cards and stolen sapphires lead the Hardy into danger on Vampire Trail!