Reacher is one of Amazons most popular and successful shows, and each season is based on the original novels by Lee Child. For the first three seasons, the show has taken the reliable approach of tackling one specific novel for the entirety of the season, starting with the first book Killing Floor and most recently handling 2003s Persuader. With the Reacher season 4 officially confirmed, its almost certain that the show will choose another of Childs stories to adapt – but it hasnt yet been announced which book that will come from.