The Master was shut up in his study, hard at work.

And, for once, he had not remembered to call Lad to a resting place on the study rug; before closing the door on the outside world.

Alone and bored, the collie had wandered into the woods; in quest of possible rabbits to chase or squirrels to tree.

Finding the sport tame, he started homeward.

Midway down the drive, his supersensitive nostrils caught the whiff of alien humans on the Place.