Alan Ritchson may have had a great idea for which novel to adapt for Reacher, but something got in the way. Reacher is based off of Lee Child's Jack Reacher series, which began in 1997. While the first season does adapt the debut novel, Killing Floor, the subsequent seasons of Reacher proceed to jump around, adapting the novels out of their original release order. This is made possible because the novels are standalone stories, carrying over the same protagonist but still self-contained enough to understand without the preceding books' immediate context. Related All 4 Seasons Of Reacher, Ranked All four...