He looked at the time table again. The train in question reached Calais at 3.31 and the boat left at 3.45. That was a delay of 14 minutes. Would there be time, he wondered, to make two long-distance calls in 14 minutes? Hardly, he thought. He considered what he himself would do if confronted with Boirac’s problem.

And then suddenly he saw it. What could be more obvious than to go by an earlier train and to break the journey at Calais? How would this time table work?

Paris dep. 9.50 a.m.
Calais arr. 1.11 p.m.
Calais dep. 3.45 p.m.
Victoria arr. 7.10 p.m.

If Boirac had done that he would have had over two and a half hours in Calais, which would have given him the opportunity he required. La Touche believed he had reached the solution at last.

But Boirac had been actually seen telephoning from Charenton. For a moment the detective’s spirits fell. But he felt he must be right so far. Some explanation of the difficulty would occur to him.

And it did. The waiter had believed Boirac was there on Monday. And he must have been! In some way he must have faked the telephoning. There could be nothing else for it.

Another point occurred to him. Surely, he thought, the telephone operator always mentions the name of the calling town in inter-urban calls? If Boirac had called up his office from Calais, would not the operator have said, ‘Calais wants you’? If so, how had the manufacturer been able to deceive his butler and chief clerk?

This was undoubtedly a difficulty. But he put it on one side as he began to think how this new theory could be tested.

First he would go again to the Charenton waiter and explain the importance of settling the day on which Boirac lunched. Perhaps the man would now be able to recall some circumstance which would make this clear. Next he would find out from François and Dufresne whether any phrase such as ‘Calais wants you’ had been used by the telephone operator. This inquiry, he noted, must be made with great skill, so as to avoid rousing Boirac’s suspicions should either man repeat the conversation. From the telephone central at Calais, if not at Paris, he could doubtless find if calls were made from the former town to the latter at the hour in question, and he might also find that some one answering to the description of Boirac had made those calls. Finally, it might be possible at Ostend to get information about the Brussels call.

Inquiries on these points should reveal enough to either confirm or disprove his theory.