When an apparent earthquake, in a sleepy Wiltshire town, creates a rupture in the road, a fog escapes. Holman, a government worker looking into potential misdeeds by the MOD, breathes it in and turns insane, before being successfully treated. The fog then makes its way along the south coast, turning everyone who encounters it into a maniac, until it reaches London. Published in 1975, my memories of this (read when I was in my teens) encompass three key set pieces - the gym, the pigeon fancier and the sex scene and as a more world-weary 42 year old, the gym sequence still works very well. The pigeon fancier suffers the same fate as many other `incidents' - you get to know the characters, in the full knowledge that they're going to die shortly - and the sex scene is remarkably coy (so much so that I wondered if I'd missed one). There's also a lengthy section in the middle, where Holman goes to a meeting at Whitehall, that is so full of exposition it literally stops the story dead. Having said that, this is full of terrific sequences - the church attack, the madness-induced fight that Casey (Holman's girlfriend) and Holman have and the superb Bournemouth sequence, which is truly brilliant, whilst making you cringe at the sheer scale and terror of it. The climax descended a little too much into 50s/60s sci-fi tropes for me, but a good read nonetheless and it still packs a solid punch. Well worth a look.