," said the man, smiling slightly. And Cairn entered the
cab.

The cabman drew up at a point some little distance beyond, from whence
he could watch. Two minutes later Ferrara came out and was driven off.
The pursuit commenced.

His cab, ahead, proceeded to Westminster Bridge, across to the south
side of the river, and by way of that commercial thoroughfare at the
back of St. Thomas' Hospital, emerged at Vauxhall. Thence the pursuit
led to Stockwell, Herne Hill, and yet onward towards Dulwich.

It suddenly occurred to Robert Cairn that Ferrara was making in the
direction of Mr. Saunderson's house at Dulwich Common; the house in
which Myra had had her mysterious illness, in which she had remained
until it had become evident that her safety depended upon her never
being left alone for one moment.

"What can be his object?" muttered Cairn.

He wondered if Ferrara, for some inscrutable reason, was about to call
upon Mr. Saunderson. But when the cab ahead, having passed the park,
continued on past the lane in which the house was situated, he began
to search for some other solution to the problem of Ferrara's
destination.

Suddenly he saw that the cab ahead had stopped. The driver of his own
cab without slackening speed, pursued his way. Cairn crouched down
upon the floor, fearful of being observed. No house was visible to
right nor left, merely open fields; and he knew that it would be
impossible for him to delay in such a spot without attracting
attention.

Ferrara's cab passed:

"Keep on till I tell you to stop!" cried Cairn.

He dropped the speaking-tube, and, turning, looked out through the
little window at the back.

Ferrara had dismissed his cab; he saw him entering a gate and crossing
a field on the right of the road. Cairn turned again and took up the
tube.

"Stop at the first house we come to!" he directed. "Hurry!"

Presently a deserted-looking building was reached, a large straggling
house which obviously had no tenant. Here the man pulled up and Cairn
leapt out. As he did so, he heard Ferrara's cab driving back by the
way it had come.

"Here," he said, and gave the man half a sovereign, "wait for me."

He started back along the road at a run. Even had he suspected that he
was followed, Ferrara could not have seen him. But when Cairn came up
level with the gate through which Ferrara had gone, he slowed down and
crept cautiously forward.

Ferrara, who by this time had reached the other side of