Five Go Mad on Mescalin (1983)

On their way to stay with Mrs French at Hot Turkey Farm, the Famous Five hear on the radio their Uncle Quentin's escaped prison. Arriving at the farm they're appalled to meet the vulgar millionaire, Mr Budweiser, and his spoilt son, Willy. Julian and Dick are so incensed, they sleep outdoors where they spy 2 heavies being secretly villainous. The trail leads to Love Island, where they discover Uncle Quentin and his boyfriend Toby.