A new solar generator has been designed to power the town of Monte Bianco. Coincidently, this is where Lady Penelope and Parker are spending their holiday. Unfortunately, the solar deflector is struck by lightening and begins to buckle and collapse. When the storm passes, moonlight is deflected towards Monte Bianco by the damaged deflector. This is not a problem for the time being, but it is quickly spotted that reflected sunlight would have much more devastating consequences in the morning. Lady Penelope tries to contact Jeff, but cannot get a signal in the valley that they are in, and sets off towards the sea, where there is no interference, leaving Parker with instructions to keep the other holidaymakers inside the hotel. He sets up a bingo game in the hotel and masquerades as 'Lord Parker' in order to get the other guests to join in.

Lady Penelope drives up to the deflector as the boys arrive. Brains goes down to take a look, and removes his safety harness, against Virgil's orders, because it is getting in his way. He attaches a clamp to the deflector, but it does not move as the gears are jammed.

The hotel is already beginning to smoke!

Brains remembers about a 'new device' and tells Scott to use it. Whilst he frees the rotation gear, Thunderbird 1 spreads black smoke that obscures the sun enough to stop the deflection damaging the hotel further.

Virgil manages to tilt the deflector away from the town, but Alan sees Brains fall when the mountainside gives way, and the deflector lands on top of him! However, Brains radios in to let them know that he is safe, and what they saw fall was the protective suit that he had taken off.