On the planet Smilonda the top holiday destination in the 423rd century, a disgruntled holiday-maker, Grone, plans his revenge on all the tourists who have spoilt the place. Grone has been visiting regularly since a child and remembers the planet in the old days, when it was lovely and peaceful. After digging a hole and burying Grone in the sand up to his neck, the Doctor points out that Grone doesn't own the universe and he would be better off trying to be a bit friendlier and having some fun. Very soon Grone is using the crab again, but this time as an attraction to entertain the children.