"It doesn't look as if we're goin' to find your friend," Salty remarked after he had rowed a quarter of a mile upstream. "We're almost to Heath's button factory now. I'll anchor here."
The man had located a bed of clams in the shallow water. He asked the girls to balance his fish basket on the gunwale, then waded in to dig the clams from the mud and sand with his rake.
As he tossed them, one by one, he kept singing snatches of familiar sea songs.
"Basket's full," Nancy called several minutes later.
Salty got into the boat and started off again. As they rounded a bend, the girls saw a large, square building set some distance back from the shore. The banks nearby were littered with discarded bits of clamshells.
"That's the Heath button factory," Salty said. "She's sure gone to pieces."
Nancy gazed curiously at the neglected brick structure. Vines which had grown up the building's walls lay thick on the shingle roof and all the windows were broken.
Suddenly Nancy spotted two figures near the factory entrance. As they vanished into the building, Salty pointed to an object hidden near some bushes.
"A boat!" he exclaimed. "And her prow's damaged, too!"
The bow of the boat had been drawn up on the sand. Nancy and George recognized it immediately as the blue-and-white craft that had struck them!
"Oh, Salty, please pull in here!" Nancy begged.
As he did, she told him about the men.
"Humph!" Salty grunted. "I'll bet ye a mess o' clams they ain't got no right in there!"
Nancy nodded. "I want to talk to them. Will you stay here near the damaged boat? If the men come out, try to hold them until we get back."
The sailor did not like being left out of the search, but before he could protest, the girls were splashing through knee-deep water to shore.
CHAPTER VIA Mysterious Explosion
Nancy and George had to cross a stretch of low, marshy land in order to reach the old button factory. Their sneakers, already water-soaked, became caked with mud. The girls were grateful for the high wild grass that screened their approach.
"You know," Nancy said, "those two men looked familiar."
"Who are they?"
"I'm not sure, but one of them was thin and wore a blue cap like the fellow who crashed into our motorboat. The other resembled Daniel Hector, the lawyer."
While still twenty yards from the factory, the girls were startled to hear the sound of hammering. The pounding noise came from inside the building.
"I wonder what those men are doing in there," Nancy said, cautiously pulling aside the tall vines.
"Maybe they're workmen who were sent to repair the place," George replied.
Nancy offered no comment. It was possible that Daniel Hector had brought another man to the property either to inspect it, or to do some work. But she seriously doubted this.
As the girls moved closer, the hammering ceased. Though they waited several minutes, it did not resume.
"We may have been seen by the men," Nancy said. "I hope they haven't left."
When George and Nancy had pushed through to the end of the marsh, they saw that the front door to the factory stood wide open. Nancy peered inside. A long corridor opened into several offices and led to a large workroom at the rear. No one was in sight.
As the girls started along the hallway, they heard retreating footsteps. They glanced out a dirt-smudged window and noticed two men running in the direction of the river.
"Oh, Nancy," George exclaimed, "they must have heard us!"
"They're going to their boat!" Nancy said excitedly.
Already the men were well hidden by the high marsh grass. The girls ran quickly toward a rear door, with Nancy far in the lead. As they neared it, deafening sounds of an explosion filled the air. The walls of the factory rocked. A huge amount of plaster crashed down between the girls.
"Nancy!" George cried out in panic as she gazed at the high pile of debris that separated them. One whole corridor wall had caved in.
"Nancy must be buried underneath it!" George thought in horror.
The air was thick with white dust. Coughing and choking, George frantically began to pull away boards and chunks of plaster.
In the meantime the two men, who had paused in the tall grass, were just about to go back to the factory when they heard someone running up the path. Salty, fearful for the girls' safety, was racing toward the building, clam rake over his shoulder. He passed within a few feet of the men, but did not see them.
"Oh dear! Oh dear!" he kept mumbling. "I hope nothin's happened to the lassies!"
He found George still digging feverishly at the pile of debris.
"Salty!" the girl cried. "I can't find Nancy! She must be buried!"
The old man began raking furiously at the pile of plaster that blocked the corridor. At that moment Nancy was lying stunned on the floor of a closet some distance from where her friends were working. The force of the explosion had hurled her into the large storage closet, then the door had slammed shut. The corridor ceiling had fallen, sealing off the entrance to the closet.
When she regained consciousness Nancy found herself in total darkness and wondered where she was. Slowly the dazed girl got to her feet and felt around her prison. At last she found a door and tried it. It would not budge, and there was no other exit.
"What'll I do?" she thought. "And where is George?"
Suddenly Nancy heard her name being called. With all her strength she pushed against the door. It yielded slightly. Through the crack she shouted, "George!"
"Nancy! Where are you?" came a muffled reply.
"Here! In the closet!"
Salty and George leaped across the rubble. With the rake and their hands and feet they cleared away enough of the debris to free Nancy. As she squeezed outside, Salty mumbled: "Thank goodness you're alive!"
George embraced her friend in excited relief. "You feel all right?"
"I think so. What caused the explosion?"
Suddenly Nancy recalled the two men who had run from the building. "What became of those men who were in here? Did you see them, Salty?"
The clam digger shook his head. "I saw no one."
Nancy, George, and Salty plunged through the marsh grass toward the riverbank. The damaged motorboat was no longer there.
"Those rascals sneaked away, drat 'em!" Salty muttered in disgust. "Do you think that makes 'em guilty, Nancy?"
"Guilty on two counts," the girl replied. "Guilty of damaging the boat I rented, and most likely, guilty of causing the explosion."
"But why set off an explosion?" George asked.
Nancy shrugged. She did not want to mention any of her theories just yet, but it occurred to her that Daniel Hector may have been covering up some incriminating evidence against himself. Mrs. Fenimore had vehemently declared that she did not trust the lawyer.