The summer after the snowy adventures in WINTER HOLIDAY and the D's learning to sail in COOT CLUB, the three sets of children (the Swallows, the Amazons, and the D's) converge on the lake again for their vacation. (By the chronology of the series, it's summer of 1932.)

However, there's complications. Only one boat, so they can't all sail. Camping is difficult because Mrs. Blackett is distracted with redecorating, and also because it's an especially dry summer there and the locals are paranoid of fires.

The children  hear rumors of gold in the hills from a local miner, and decide to prospect themselves while Uncle Jim is on his way back from a failed mining expedition in South America. They soon find a lanky stranger, dubbed "Squashy Hat," seems to be prospecting himself, and they view him as a dangerous competitor.

The kids face all sorts of challenges, from camping near a farm whose owner won't let them cook for themselves and insists they sleep near the house....to dealing with the pigeons of the title that keep them in touch with the Amazon's mum....to finding the possible gold mine....to very real dangers, including a cave-in in an abandoned mine to a runaway brush fire.