Alien threats come in many forms - and many different hues. A charity shop where customers vanish, a 1920s gentleman's club besieged by giant plants, and a distant colony planet where death hides in darkness - wherever they manifest, the Doctor is on hand to fight every shade of fear... 4.1 The Colour of Terror by Lizzie Hopley Mrs Bevell wants to keep the star rating for her charity shop at any cost - but why does she stock so many items of one particular shade? When West Morebry residents start to notice disappearances, the Doctor assembles a motley band to do battle... with the colour red! 4.2 The Blooming Menace by James Kettle Toby Entwhistle and his bachelor chums in the Fellows Club are falling victim to a plague - of marriage! The chaps are all besotted by giant flowers - but Toby’s new valet seems to know what’s going on. The Doctor could be London's only hope... 4.3 Red Darkness by Roy Gill The sunlight from Solis Kailya could revolutionise colony farming. While his mother researches its properties, Callen and his seeing (and talking!) dog Doyle meet a new arrival - and discover an impending threat... The Vashta Nerada are closing in, and they are not alone.