Financial disaster looms for Grand Fenwick when the current vintage of its only export, wine, starts exploding in would-be consumers' faces.

Prime Minister Mountjoy decides to ask the United States for a loan, ostensibly to fund its entry in the race to the Moon, but actually to save the duchy (and install modern plumbing so he can have a hot bath).

The devious politician knows that the Americans will not believe him, but will consider the half million dollars he is asking for to be cheap propaganda supporting their hollow call for international co-operation in space.

Mountjoy asks resident scientist Professor Kokintz to arrange a small explosion during the "launch" of their lunar rocket to make it look like they have actually spent the money as intended.

Maurice Spender, a bumbling spy sent by the suspicious British, is given a tour of the ship, including the shower heads converted into attitude jets, and reports back to his bosses that it is all a hoax.

When the Americans and Soviets try to race home to salvage some sort of propaganda coup, they almost enter the wrong ships and then, when they attempt lift-off, both descend deep into the lunar dust.