The Cipher of Leonardo

From Geoffrey Chaucer Hath a Blog:
Myn gentil rederes alle, ich dide thynke ich wolde teste out sum newe materiale on yow bifor ich do trye to publishe yt. Ich haue layde plannes for to enditen what ich do calle a ‘romaunce thrillere’ – all of the actioune of a romaunce, but wyth sum puzzle solvynge [...]