Doc Savage #5

He called himself X Man—X for unknown. Found dressed in a Roman toga, wandering the ruins of an old fort from Caesar's day, X Man was thrown into a madhouse, his origins and real name impossible to discover. What is the strange connection between this supposed madman, a multi-headed sea creature discovered swimming in a Scottish loch, and a pair of rogues willing to kill to control the secret of the mysterious X Man? Archeologist Johnny Littlejohn braves sudden death to find out the shocking truth, drawing Doc Savage into the exciting quest in his fifth audiobook appearance.