Much in need of a holiday, Mel and the Doctor head for Paradise Towers: a luxury man-made planet with sparkling fountains, sunny streets, exotic flowers and a shimmering blue swimming pool. But when the TARDIS materialises in a dark, rubbish filled, rat-infested alley it seems that this particular Paradise has turned into Hell! Pursued by rogue cleaning machines, authoritarian caretakers and old ladies with strange eating habits, the Doctor and Mel track down the source of the chaos to one mysterious character – the designer of Paradise Towers, the Great Architect himself …