"Maybe we are getting somewhere," Steve corrected. "You found something today that may be the balloon payload. You also found out that people from the mansion were interested in your activities, but didn't want to be seen. It's obvious that the object you found must be recovered. You've got a plan. I'm sure of it."
"We do," Rick agreed.
Scotty added, "First of all, we have to warn Orvil Harris. If he goes crabbing in the middle of the night, he might foul a prop on the stake we left there."
"The people in the mansion can't be suspicious of Orvil," Rick went on. "He goes crabbing there every day. They must be used to him by now. Suppose we call him, to warn him about the stake, and to see if he'll help out."
"He'll be glad to help," Scotty said.
"Help how?" Steve asked. "By providing cover?"
Rick nodded. "Exactly. Scotty and I will suit up, so our skins won't show at night, and have our Scuba equipment on. Harris could come by and take the runabout in tow with us in it. We would drop off near the creek entrance and push the runabout into the channel where it would be hidden. Then we would swim into the cove and recover the object. With two of us, it would be a cinch to find the fish line."
"If the thing is too heavy to swim with," Scotty went on, "we'll hand it into Orvil's boat. Of course we'll pull up the sapling and hand that to Orvil. If the gadget is light, we'll swim back to the runabout with it, push the runabout away from the cove into the river, and then get aboard and come home."
Rick concluded, "With Orvil's motor going, no one would hear our bubbles."
Steve had followed the plan carefully. "Fair enough," he agreed. "It's a good plan. No one will see you enter the cove, and no one will see you leave. There will be only Orvil Harris catching crabs as usual."