They climbed the back fence and fled up the alley.

They turned into Sam's yard, and, without consultation, headed for the cellar doors, nor paused till they found themselves in the farthest, darkest and gloomiest recess of the cellar.

There, perspiring, stricken with fear, they sank down upon the earthen floor, with their moist backs against the stone wall.
Thus with boys.

The vague apprehensions that had been creeping upon Penrod and Sam all afternoon had become monstrous; the unknown was before them.

How great their crime would turn out to be (now that it was in the hands of grown people) they did not know; but, since it concerned a horse, it would undoubtedly be considered of terrible dimensions.
Their plans for a reward, and all the things that had seemed both innocent and practical in the morning, now staggered their minds as manifestations of criminal folly.