Harry Harrison 
Deathworld [EPUB ebook] 
Deathworld Book 1

The planet was called Pyrrus, a strange place where all the beasts, plants and natural elements were designed for one specific purpose: to destroy man.The settlers there were supermen, twice as strong as ordinary men and with milli-second reflexes. They had to be. For their business was murder.It was up to Jason din Alt, interplanetary gambler, to discover why Pyrrus had become so hostile during man’s brief habitation.