Ever since he had come to the conclusion that Lady Arabella was trying to steal the treasure-chest, he suspected nearly everyone of the same design, and made it a point to watch all suspicious persons and places.

As Adam was engaged on his own researches regarding Lady Arabella, it was only natural that there should be some crossing of each other's tracks.

This is what did actually happen.
Adam had gone for an early morning survey of the place in which he was interested, taking with him the mongoose in its box.

He arrived at the gate of Diana's Grove just as Lady Arabella was preparing to set out for Castra Regis on what she considered her mission of comfort.

Seeing Adam from her window going through the shadows of the trees round the gate, she thought that he must be engaged on some purpose similar to her own.
So, quickly making her toilet, she quietly left the house, and, taking advantage of every shadow and substance which could hide her, followed him on his walk.
Oolanga, the experienced tracker, followed her, but succeeded in hiding his movements better than she did.