her face under the big green hat.  It was very pretty and young, and the hair was fair.  She wore a white coat, but it was open in front and showed her evening frock of pale green.  When she lifted her skirt I saw the buckles sparkling on her satin shoes.  It was the young lady for whom you are advertising, I am sure.  She remained standing just for a moment without moving, while Mme. Rossignol got out.  I was surprised to see a young lady of such distinction in Mme. Rossignol’s company.  Then, still holding her skirt up, she ran very lightly and quickly across the pavement into the dark house.  I thought, monsieur, that she was very anxious not to be seen.  So when I saw your advertisement I was certain that this was the young lady for whom you are searching.  “I waited for a few moments and saw the carriage drive off towards the stable at the end of the street.  But no light went up in any of the rooms in front of the house.  And M. Gobin was so fretful that I dropped the corner of the blind, lit the candle, and gave him his cooling drink.  His watch was on the table at the bedside, and I saw that it was five minutes to three.  I will send you a telegram tomorrow, as soon as I am sure at what hour I can leave my husband.  Accept, monsieur, I beg you, my most distinguished salutations.

“Marthe Gobin.”

Hanaud leant back with an extraordinary look of perplexity upon his face.  But to Ricardo the whole story was now clear.  Here was an independent witness, without the jealousy or rancours of Helene Vauquier.  Nothing could be more damning than her statement; it corroborated those footmarks upon the soil in front of the glass door of the salon.  There was nothing to be done except to set about arresting Mlle. Celie at once.

“The facts work with your theory, M. Hanaud.  The young man with the black moustache did not return to the house at Geneva.  For somewhere upon the road close to Geneva he met the carriage.  He was driving back the car to Aix—­” And then another thought struck him:  “But no!” he cried.  “We are altogether wrong.  See!  They did not reach home until five minutes to three.”

Five minutes to three!  But this demolished the whole of Hanaud’s theory about the motor-car.  The murderers had left the villa between eleven and twelve, probably before half-past eleven.  The car was a machine of sixty horse-power, and the roads were certain to be clear.  Yet the travellers only reached their home at three.  Moreover, the car was back in Aix at four.  It was evident they did not travel by the car.

“Geneva time is an hour later than French time,” said Hanaud shortly.  It seemed as if the corroboration of this letter disappointed him.  “A quarter to three in Mme. Gobin’s house would be a quarter to two by our watches here.”

Hanaud folded up the letter, and rose to his feet.

“We will go now, and we will take this letter with us.”  Hanaud looked about the room, and picked up a glove lying upon a table.  “I left this behind me,” he said, putting it into his pocket.  “By the way, where is the telegram from Marthe Gobin?”