There are various synonyms for the phrase "follows the book," which generally refers to someone who strictly adheres to rules or procedures. Some possible alternatives include "plays by the rules," "adheres to protocol," "follows protocol," "sticks to the plan," "goes by the book," "abides by regulations," "complies with guidelines," or "observes standard operating procedures." Depending on the context, other phrases such as "follows the script," "follows the recipe," or "follows the instructions" may also be applicable. These synonyms all convey the idea of someone who follows established norms or procedures, rather than taking a more creative or innovative approach.