The horses kept to the gait of the leaders.

Helen, discovering it unnecessary, ceased attempting to guide Ranger.

There were dim shapes in the gloom ahead, and always they gave Helen uneasiness, until closer approach proved them to be rocks or low, scrubby trees.

These increased in both size and number as the horses progressed.

Often Helen looked back into the gloom behind.
This act was involuntary and occasioned her sensations of dread.