CHAPTER TWENTY THREE.
TOM THE BOAT-BOY EARNS FOUR-AND-SIXPENCE.
Riddell, as he read over and over again the mysterious document in his hand, hardly knew what to make of it.
It looked like a clue, certainly.

But who had sent it?
Was it a friend or an enemy; and if the latter, might it not just as likely be a hoax as not?
He examined the disguised writing letter for letter, but failed to recognise in it the hand of any one he knew.

He called back Cusack and cross-examined him as to how and when the letter was brought to his study; but Cusack could tell him nothing.

All he knew was that when he went in to look after Riddell's tea that afternoon, it was lying there on the table.

He couldn't say how long it had been there.