infrared motion-picture film."

So that was it. Rick grinned. "I hope your new invention told you I asked the film company to send the bill to me and not to you."

"It did. The bill actually was addressed to the Spindrift Foundation, attention Mr. Brant. Since I didn't know which Mr. Brant was meant, I opened it. Don't worry, Rick. I'll let you pay it."

"Thanks, Dad," Rick said. "But don't make any sacrifices. You can pay it if you want to."

"Don't want to," Hartson Brant replied. "I haven't the slightest use for motion-picture film."

"Because Rick has the only motion-picture camera on the island," Scotty finished. He frowned at his friend. "Keeping secrets, huh?"

"I'm not sure it will work," Rick explained. He hated to brag about an idea and then have it turn out to be a dud. Consequently, he seldom mentioned that he was working on anything until he knew it would be successful.

"What does the film have to do with penetrating the darkness?" Jerry Webster inquired.

Rick caught the look of interest on his father's face. "Ask Dad," he said. "The electronic mind reader probably has told him all about it."

"Of course." The scientist chuckled. "Rick is planning to take movies at night without lights."

Jerry looked skeptical. "How?"

Rick stood up. "Long as we've started talking about it, I may as well show you."

The others rose, too. As they did so, a shaggy little dog crawled from under Rick's chair where he had been napping.

"Dismal and I will put the cake away," Mrs. Brant said.

At the sound of his name the pup rolled over on his back and played dead, his only trick. Rick bent and scratched his ribs in the way the pup liked best. "Go with Mom," he commanded. "Come on, the rest of you. Maybe I can get some free advice from the director of the Spindrift Foundation."

Hartson Brant smiled. "If you're looking for a technical consultant, Rick, my price is very reasonable."

"It would have to be," Rick admitted ruefully. "I've spent my entire fortune on this thing."

"The whole dollar," Scotty added.

The boys' rooms were on the second floor in the north wing of the big house. But where Scotty's was usually neat as a barracks squad room, the result of his service in the Marines, Rick's was usually a clutter of apparatus. Living on Spindrift Island with the example of his father and the other scientists to follow, it was natural that he should be interested in science. He was more fortunate than most boys with such an interest, because he was permitted to use the laboratory apparatus freely and his part-time work as a junior technician gave him spending money with which to buy equipment. Another source of revenue was his little two-seater plane. He was the island's fast ferry service to the mainland.

His room was neater than usual at the moment because he had not bothered to connect most of his apparatus after returning from the South Pacific. The induction heater that he used for midnight snacks was in a closet. His automatic window opener was not in use, nor was his amateur radio transmitter.

He opened a workbench built into one wall and brought out a motion-picture camera. It was a popular make with a type of lens mount that permitted fast switching of lenses. It used one-hundred-foot rolls of 16-millimeter film. He put the camera on the table, then from a cupboard he brought out what appeared to be a searchlight mounted on top of a small telescope.

"That's a sniperscope!" Scotty exclaimed.

Rick nodded.

"No reason why it shouldn't work very well, Rick," Hartson Brant said.

Jerry Webster sighed. "Excuse my ignorance. What's a sniperscope?"

"They were used during the last war," Scotty explained. He picked up the unit and pointed to the light, which was about the size and shape of a bicycle head lamp. "This searchlight throws a beam of black light. Rick would call it infrared. Anyway, it's invisible. The telescope is actually a special telescopic rifle sight which will pick up infrared. You can use the thing in total darkness. Mount it on a rifle and then go looking for the enemy. Since he can't see the infrared, he thinks he's safe. But you can see him through the 'scope just as though he had a beam of white light on him."

"I see," Jerry said. "Where are the batteries?"

Rick brought out a canvas-covered case that looked like a knapsack. It had a crank on one side and a pair of electrical connections. "It's not a battery," he explained. "It's a small, spring-driven dynamo."

Jerry nodded. "I get it now. You rig this thing on the camera, which is loaded with infrared film. The film registers whatever the infrared searchlight illuminates. Right?"

"That's the idea," Hartson Brant agreed. "But it isn't as simple as that, is it, Rick?"

"Far from it. I have to determine the effective range, then I have to run a couple of tests to find out what exposure I have to use, and then I have to find the field of vision of the telescope as compared with the field of the lens. A lot depends on the speed of the film emulsion. That will limit the range. The searchlight is effective at eight hundred yards, but I'll be lucky if I can get a picture at a quarter of that."

"Where did you get the sniperscope?" Scotty wanted to know.

"By mail. I read an ad in a magazine that advertised a lot of surplus war equipment, including this."

"You might have said something about it," Scotty reproached.

Rick grinned. "You were too busy working on the motorboats. I knew you couldn't have two things on your mind at once."

Since the boys returned from vacation, Scotty had been overhauling the engines on the two motorboats which were used, along with Rick's plane, for communication with Whiteside, the nearest town on the mainland.

"I have a book downstairs that you'll find useful, Rick," Hartson Brant said. "It gives the comparative data on lenses. It may save you some figuring."

"Thanks, Dad," Rick replied. "I may have to ask your help in working out the mathematics, too. Anyway...." He stopped as the phone rang.

In a moment Mrs. Brant called. "Jerry, it's your paper."

"Something must have popped!" Jerry ran for the door.

Rick hurried after him, Scotty and the scientist following. The Whiteside Morning Record, for which Jerry worked, must have had something important come up to phone Jerry on his night off.

In the library, Jerry picked up the phone. "Webster. Oh, hello, Duke. Where? Well, why can't one of the other guys cover it? Okay, I'll be on my way in a minute. How about a photographer? Hold the phone. I'll ask him." He turned to Rick. "Duke wants to know if you can take your camera and cover a story with me. A trawler went ashore down at Seaford."

Rick nodded quick assent. The little daily paper had only one photographer, who evidently wasn't available. It wouldn't be the first time he had taken pictures for Duke Barrows, the paper's editor.

"He'll do it. We're on our way." Jerry hung up. "Have to work fast," he said. "We start printing the paper at midnight."

"It's nine now," Scotty said.

Rick ran upstairs and opened the case containing his speed graphic, checking to be sure he had film packs and bulbs, then he snapped the case shut and hurried downstairs with it. Jerry and Scotty were waiting at the door.

"Don't stay out too late," Mrs. Brant admonished.

Dismal whined to be taken along.

"Sorry, boy." Rick patted the pup. "We'll be home early, Mom. Want to come along, Dad?"

"Not tonight, thanks," the scientist replied. "I'll take advantage of the quiet to catch up on my reading."

In a moment the three boys were hurrying toward the hook-shaped cove in which the