The Boy Scouts in Russia - Harold L. Goodwin

Thrown out of Russia by a powerful relative, a young American Boy Scout, Fred Waring, meets his Russian cousin, Boris Suvaroff, and together they discover the secrets of the advancing German army. Through perilous escapes, secret passages, and being captured as a spy (by both sides), they deliver their information to Russian intelligence. But Fred now has to face an obstacle even bigger than he had realized.
John Blaine is a pseudonym of Harold L. Goodwin. (Kangaroo)