Guardian Genius
No.256
Set by Claw

Each clue’s wordplay indicates an extra letter: these spell out an instruction. Following this will take the solver on a journey. However, the journey will quickly be thwarted in a couple of places. To resume it, the solver must change one letter each time. The journey will resume at pace until close to the end, when one final letter change will complete a release from 50 years ago this month. The original letters give a Homeric summary of its conclusion. Final entries are all real words or names.