Why should they desire to gain possession of the girl?
It could not be money, or the hope of ransom.
What then?
Was it some accident which had involved her in the toils prepared for another?
If so, were those unexpected orders for Major McDonald a part of the conspiracy, or had their receipt complicated the affair?
The Sergeant was a soldier, not a detective, and could only follow a straight road in his investigation.

He must circle widely until he found some trail to follow as patiently as an Indian.

There would be tracks left somewhere, if he could only discover them.

If this was a hasty occurrence, in any way an accident, something was sure to be left uncovered, some slip reveal the method.

He would trace the movements of the father first, and then search the saloons and gambling dens for the two men.