However, I don't think there is any occasion for us to worry about moving
any more of the panels, seeing that we can get through now quite easily.
Wouldn't it be just as well to put all the lights out?"

"I haven't thought of that," Venner muttered. "On the whole, it would be
exceedingly injudicious not to extinguish all the lights. We had better
go on at once, I think, and get it over."

The house was reduced to darkness, and very quietly and cautiously the
two adventurers crept through the panel. They were in the hall on the
other side, of which fact there was no doubt, for they stepped at once
off a marble floor on to a thick rug which deadened the sound of their
footsteps. They had, naturally enough, expected to find the whole place
in darkness, and the tenant of the house and his servants in bed. This,
on the whole, would be in their favor, for it would enable them to take
all the observations they required with a minimum chance of being
disturbed.

A surprise awaited them from the first. True, the hall was in darkness,
and, as far as they could judge, so was the rest of the house. But from
somewhere upstairs came the unmistakable sound of a piano, and of
somebody singing in a sweet but plaintive soprano voice. Gurdon clutched
his companion by the arm.

"Don't you think it is just possible that we have made a mistake?" he
whispered. "Isn't it quite on the cards that this is a genuine affair,
and that we are intruding in an unwarrantable manner upon some
respectable private citizen? I am bound to say that that beautiful voice
does not suggest crime to me."