May Books 3) Island of Death, by Barry Letts

Barry Letts' last novel, published in 2005 just after New Who began, but taking the Third Doctor, Sarah Jane Smith and the Brigadier to investigate a strange cult based around a mind-altering drug and rescuing Sarah's gormless assistant Jeremy (from The Paradise of Death and The Ghosts of N-Space). It's not great, to be honest; the story rambles and characters make rather arbitrarily stupid decisions in order to prolong the plot. But we should take it as what it is, a farewell note to the series from one of its veteran producers.