Cold Fusion is an original novel written by Lance Parkin and based on the long-running British science fiction television series Doctor Who. It features the Fifth Doctor, with Adric, Nyssa, and Tegan, immediately after Castrovalva. Also appearing is the Seventh Doctor, with Chris and Roz, from between the Virgin New Adventures novels Return of the Living Dad and The Death of Art. It was the only one of the Virgin Doctor Who novels to feature more than one Doctor. Source: Wikipedia (en)