THE INVISIBLE BOX-MURDERS Four men have mysteriously died after receiving an innocuous box that vanishes within minutes of the murder! Doc and his crew race to crack the case -- because Doc is suspect number one! PERIL IN THE NORTH 250 people are abandoned in the Arctic wilderness at the mercy of a murderous madman. Only Doc Savage can prevent wholesale slaughter on ice. Following a gun- and bomb-blasting battle on the New York docks, the Man of Bronze and his crew face northward to smash a sinister plot -- and to expose the cruel secret of a bloodthirsty foreign dictator!