Matt Helm - The Interlopers

This time Mac has gone too far. For Helm to impersonate a Communist courier to whom he bears no resemblance is suicide, and that isn't all. Someone wants to get the layout of the Alaskan North-west Coastal Defence System, but they aren't the good guys or the bad guys. So who the hell are they? And who is the mysterious Holz that Helm is meant to kill?