Secret Of The Dragon's Scales: Book Four book by Derek Hart

Secret of the Dragon's Scales continues the adventures of Gavin Kane, Emily Scott, and Bunty Digby, fifteen-year-olds who make the best of their young lives in England during the autumn of 1943. World War II rages on, but the tide seems to have turned in favor of the Allies. Three times previously, the teens have defeated Nazi plans to defeat England using evil magic, and three times, there have been new alliances formed with creatures from the hidden worlds of legend and fable. Yet once again, Heinrich Himmler is determined to unleash another strange and horrible weapon from deep within Nazi Germany, while halfway across the world, Allied armies are now tenaciously fighting the Japanese Empire.