Crablogger 1, a huge tree-felling machine, arrives at base camp in South America in preparation for its first mission. That evening, the base commander, Jansen, takes the Crablogger crew for a meal at a local restaurant in nearby San Martino, as they are not due to start work until the following day.
When Crablogger sets off from base camp the next morning, crewmen Peterson and McColl both collapse, the victims of food poisoning - and the now-rudderless Crablogger veers off course, heading straight for San Martino...
A Path of Destruction[]
Ordered to throw the remote switch, McColl is unable to reach it in time before he passes out...leaving Crablogger in automatic mode. To make matters worse, the vehicle must be constantly relived of the supplies of wood pulp that it produces while in motion; for if the machinery jams, the resulting explosion of the Superon-fuelled atomic reactor would lay waste to everything within a 50-mile radius. The one way to stop the huge machine is to active the secret reactor shut-down procedure from inside the control cabin, which can be accessed only through the roof of the vehicle...
Only One Outfit Can Handle This Situation...[]
Jansen calls International Rescue, and Scott sets off in Thunderbird 1; while Jeff apprises Lady Penelope of the situation, and what she must now do...
Shut-down Procedure[]
Lady Penelope travels to Jim Lucas' House and gets the designer of Crablogger to give her the shut-down procedure he alone knows. Having stored the information on her Micord-4 recorder, she tosses the instrument to Parker, who in turn plays it for John Tracy, listening in from Thunderbird 5. John then relays it to Brains, aboard Crablogger...
Shut-down[]
Thunderbird 2 arrives at the danger zone; and Virgil and Brains quickly set off in the Mobile Crane, driven at top speed by Scott. When the crane catches up with Crablogger, Scott lifts the boys onto its roof. Virgil sets to work cutting through it, and gains access to the control cabin. The vehicle is now heading straight for the San Martino Dam! Lady Penelope transmits Lucas's information, and at last Brains can activate the reactor's shut-down procedure...
Time-lag![]
Crablogger is now moving along a narrow mountain track, towards the San Martino Dam - and there's a three-minute time-lag before the machine will actually come to a full stop. Meanwhile, as Scott brings up a fuel truck, Virgil and Brains attach siphons to the fuel outlets and set about draining the tanks of the literally-explosive Superon fuel....
The End of Crablogger[]
Crablogger finally stops - but the ledge is crumbling away beneath its immense weight. Virgil and Brans use their hover packs to leap clear. The deteriorating cliff-face gives way; and, its fuel tans fully drained, Crablogger falls! The machine is completely destroyed, but the dam is saved.
