It’s that time of year again! The time in early summer when the Common is more crowded than ever and there are tennis balls all over the place.  The Wombles have to work overtime to keep up with the rubbish. Meantime, Wellington is convinced there are aliens out there and Orinoco gets hijacked in a picnic basket. Alderney and Stepney save Orinoco and, in the process, learn more about the sport of tennis than they'd been expecting! Does Wellington find his aliens?