Read it through once

After a strained moment of silence, he leaned across and said, very quietly, but watching the effect of each word upon the face of him he had sent for, “Alan, in a locked room at the top of this house, a room to which nobody but myself has access, a dead man is seated at a table. He has been dead ten hours now. Don’t stir, and don’t look at me like that. Who the man is, why he died, how he died, are matters that do not concern you. What you have to do is this—”