The testament of William S.

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...