On a time-traveling trip to feudal Japan in 1595 teenagers Dawk and Hype Faraday - from the 25th century - find themselves caught up in a baffling mystery. Dawk befriends a crazy mountain monk who claims he is stalked by a demon called a tengu. His sister Hype meanwhile bonds with a female samurai who begins to train Hype as a warrior. These two worlds collide when the tengu attack a castle town drawing the Faradays into a multi-century mystery. With Hype's samurai training and Dawk's growing knowledge of demon lore will the Faradays be able to defeat the mysterious medieval menace