‘I imagined Boirac, then, mad with his discovery on the Sunday morning, sitting down and working out a plan for vengeance. He perhaps goes on that morning to the Gare du Nord, and possibly sees them start. He follows them to London. Or, at least, he sees and follows Felix. Madame may have gone by another route. By the time he finds they have reached St. Malo his plan is worked out. He learns they are alone in the house, and he watches till he sees them go out. Then he enters by, say, an open window, and, sitting down at Felix’s desk, he forges a letter to Dupierre, ordering the companion statue to that he has already purchased. He does this in order to obtain a cask in which to pack Madame’s body, as he intends to murder her. To throw suspicion on Felix, he copies the artist’s handwriting and dries it on his blotting paper. For the same reason he signs it with Felix’s name. But he does not give Felix’s address, as he wants to get the cask himself.’ ‘Good!’ interjected Heppenstall. ‘He then comes away with his letter, posts it, telephones to Paris to know when and by what route the cask is being sent, and arranges a carter to meet it and bring it near, but not to St. Malo, instructing the carter to await him. Meantime, in some letter or telegram or other trick, he gets Felix out of the way, leaving Madame alone in the house. He rings, she opens the door, he forces his way in, and, in that little round-backed chair in the study, he throttles her. The pin falls out of the neck of the dress and lies unnoticed. Then he goes back to the carter and brings the cask into the yard. He sends the carter to the nearest inn for his dinner, unpacks and destroys the statue, and packs the body. By this time the carter has returned, and Boirac has him remove the cask, giving him instructions to send it to Paris next morning. To compromise Felix still further he has prepared the Emmie note, and he shoves this into the pocket of Felix’s clothes.’ ‘Good,’ said Heppenstall again. ‘He goes himself to Paris, gets hold of the cask at the Gare du Nord and sends it to Felix from the rue Cardinet Goods Station. He works out a tricky letter which will have the effect of making Felix claim the cask. Felix does so and the police get on his track.’ ‘By George, Clifford, you haven’t been idle. I shouldn’t wonder if you are pretty near the thing. But if all that had taken place at St. Malo, do you think Felix wouldn’t have said something about it?’ ‘I think he would have. On the other hand, he may have wanted to save Madame’s memory, and if so, he obviously couldn’t mention it?’ ‘What about the charwoman?’ ‘Well, that is another difficulty. But I think a clever woman could have hidden her traces.’ ‘The theory accounts for a great many things, and I think we must adopt it as a basis for investigation. Let us now see what it involves.’