re,' he said.
'We _must_ see what it is.'

'It's very late,' hesitated Marjorie, doubtfully. 'If we are asked where
we have been, what shall we say? All our secrets will come out, and then
good-bye to all fun.'

'Oh, this won't take us long,' returned Alan, who did not intend to give
up investigations just as he appeared to be on the verge of scoring the
greatest success of the day.

As it turned out, it was fortunate indeed that the quest was not given
up, for something happened only a few days later which made their
discoveries of the utmost importance.

The narrow cleft led them, after some winding, into a comparatively wide
passage, into which the daylight was streaming through a great opening
to the right. In some excitement they ran to look out, and found, to
their delight, that they were standing at the hole in the cliff which
they had seen from the beach in Smugglers' Bay. Sure enough, there was
the stream of water flowing at their side which made the thin cascade.

'I do believe we are in the passage which leads to the ruined
summer-house!' cried Marjorie, breathlessly.

Alan was for trying it at once, but here Marjorie's counsels did
prevail. She pointed out how low the sun was, and that probably they
were very late for the schoolroom tea already.

'Right you are,' said Alan, looking longingly up and down the passage
and walls, which stretched away into deep but--to him--alluring gloom.
'We will come again to-morrow. We must slip away directly after
breakfast; and mind we don't let anybody see or follow us. It will be a
feather in our caps if we can get into the ruined summer-house without
troubling old Peet for the key.'

'But,' said Marjorie, after a long pause, during which she was thinking
deeply, 'what if Thomas knows of this way in?'

'He can't,' returned Alan, 'or he would have been before, and got all he
wanted.'

'Then,' replied Marjorie, after another pause for thought, 'you may be
sure there is some reason: something that prevents his going up the
passage, and will prevent our going too. Thomas is sure to be up to all
dodges.'

This idea was so distasteful to Alan that he required a good deal of
persuasion before he gave up his determination to explore further.
Marjorie did persuade him, nevertheless, but next morning he could not
refrain from reproaches for having yielded to her. It turned out that
Colonel De Bohun had some business to do in the neighbouring town of
Matherton, and to