Blake & Mortimer 24 - The Testament of William S.

Captain Francis Blake, dashing head of England's MI5. Professor Philip Mortimer, world-renowned nuclear physicist. The most distinguished duo of gentleman-adventurers, battling the forces of evil and their arch nemesis Olrik around the globe, below the earth, even across time itself. The 24th adventure of Her Majesty's finest protectors!
In Venice, a boating accident leads to the discovery of a 400 year old text bearing the signature 'W.S.' and promising the truth about the 'Shakespeare mystery'. That very night, someone tries unsuccessfully to steal the precious document. The discoverer, Marquis Stefano Da Spiri, decides to send a copy of the document to a specialist of the Bard in London for stylistic authentication. As for the original, he entrusts it to an old comrade in arms from WW2: Captain Francis Blake.