An assignment from their famous detective father to track down a ring of credit-card counterfeiters takes Frank and Joe Hardy on an exciting camping trip to the Rocky Mountains. The cross-country trek with their pals Chet Morton and Biff Hooper is jinxed from the very first day. Trouble with their tent trailer is compounded by vicious harassments all the way to Colorado. Here their enemies strike at Biff's lovable bloodhound in another attempt to scare the teen-age detectives off the case. In Denver a skein of clues confuses the Hardys. How many gangs are out to get them -- one, two, or three? Strange happenings on a nearly impassable mountain lure Frank, Joe, Chet, and Biff to almost certain death before they discover the sinister reason for the danger on Vampire Trail. - Flyleaf.