John Wyndham 
The Chrysalids 

FROM THE CLASSIC SCI-FI WRITER AND AUTHOR OF THE DAY OF THE TRIFFIDS
A disturbing post-nuclear apocalypse story of genetic mutation that explores the lengths the intolerant will go to keep themselves pure.
David Strorm »s father doesn »t approve of Angus Morton »s unusually large horses, calling them blasphemies against nature. Little does he realise that his son, his niece Rosalind and their friends, have their own secret aberration which would label them as mutants.
But as David and Rosalind grow older, it becomes more difficult to conceal their differences from the village elders. Soon they face a choice: wait for eventual discovery – or flee to the terrifying and mutable Badlands . . .
 »An outstanding success » New York Times
 »Perfect timing, astringent humour. . . one of the few authors whose compulsive readability is a compliment to the intelligence » Spectator
 »Remains fresh and disturbing in an entirely unexpected way » Guardian