Disappointment at not being chosen to attend the Scout, Jamboree was doubly difficult for Mike Leach because, although Mike himself was a Queen's Scout, Donald, his brother, was selected. But Pop Leach, Mike's grandfather stepped in to bolster the boy's morale by joining Mike in a masquerade at Chard Edge to kibitz in a battle of wits staged between Don and his American Scout friend, Mervin Demont, when they set out to prove they are more skillful Scouts than their two fathers. Had they known of the serious dangers that lay in wait in the abandoned mine at Chard Edge Valley, they might have hesitated. Despite the title, scouting plays a relatively minor role in the story, serving mainly as a motivational force to align the six leading characters against a gang of thieves who have been filching coal from the mine. A boy's book, this strains adult credulity but probably wouldn't bother young readers with mine cave-ins and blood and thunder to satisfy adventure- hungry young males.