Palmer turns his biography of the rabidly anti-Semitic madman Baron Nikolai Maximilian von Ungern-Sternberg -- and his improbable reign as the last Khan of Mongolia -- into a fascinating tale of politics run amok in Mongolia and the Russian Far East. He may not have been the only White military commander to tyrannize the people of Central Asia in the wake of the Bolshevik revolution, but there's no question he was the most savage. Palmer's meticulously researched book makes for uncomfortable but fascinating reading.  (MGL66, $15.99)