Kat is given a cyberdug called Doug for her birthday. But Doug is no mere toy - he is a real cyberdug and he's happy to take Kat on his fact-finding missions among the stars. Kat has jsut been gubbed at tennis by her next-door neighbour, who's just too good at everything. But then Doug wheechs her away to Planet Perjink, the neatest, cleanest planet in the universe. They meet one of the locals, Redd, who shows them around the Swankie Loch and teaches them how to play CometBa. Perhaps when she gets back home, Kat's tennis will have improved dramatically...Kat an Doug on Planet Perjink is the second book in the popular Planet series.