This starts off with a man lying on the pavement claiming he can hear mass burrowing noises below. Perhaps unsurprisingly he is taken away to be "looked after", but after an incident at a top secret underwater facility, then a mining disaster, the authorities start to investigate in earnest - and they discover an intricate network of tunnels that have been bored under sensitive targets across the USA. It falls to "Shaw" (Kerwin Matthews) to organise the defence of the nation and thwart the cunning plan of rogue General "Chan Lu" (Martin Benson) complete with his army of henchmen, some red is green hypnosis and his menacing hawk. It reminded me of an episode of the "Man from UNCLE" this, plenty of well staged action, gadgets, gizmos and a highly pitched score that tries hard to engender some sense of peril - sadly not to be when much of the scenery is clearly made from papier-mâché! I kept expecting Christopher Lee to show up at some point.