The Mark of the Blue Tattoo by Franklin W. Dixon

menu? he wondered.
    Joe lifted the lid, then let out a low whistle. The cardboard carton was half full of cash. A few bills were singles and fives, but most were tens and twenties.
    Joe reached into the carton and pulled out a small pad of paper. The pages were perforated halfway along their length, and about a third of the pages already had the lower part torn off. On each of the stubs was scrawled a three-digit number.
    â€œSo that’s it,” Joe said out loud. No wonderGus didn’t care that much whether he sold any ice-cream cones to kiddies.
    He replaced the pad in the carton and closed the freezer, then turned to leave. But as he did, he felt the truck rock to one side. He knew what that meant. Gus had climbed back into the driver’s seat. The only way out was past him. Joe was trapped.

12 Taken for a Ride
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    Joe stood perfectly still, even though he knew that all Gus had to do was turn around to see him. Any noise, any movement might alert Gus that an intruder was in the truck. Yet Joe knew he had to get out of sight—and fast.
    Joe looked around, scanning the crowded space for a place to hide. He thought he spotted a gap between the frozen custard machine and the rear wall of the van. Could he possibly squeeze himself into it? He had to take the chance.
    Joe lifted his left foot, moved it toward the rear of the truck, and set it down as delicately as if he were walking through a flowerbed full of rare blossoms. Shifting his weight, he took anothercareful step, then another. He was more than halfway to the niche behind the custard machine when the truck shook from the vibration of the starter motor. The noise of the engine would cover any he made. Joe dashed across the last few feet and flattened himself against the wall.
    With a jolt, the Freddy Frost truck started to move. Joe tried to think calmly about his situation. Yes, he was hidden for now. But the next time Gus made a stop and came into the back, he would be bound to spot Joe. And once he knew that Joe had been inside the truck, he would guess the rest. Joe and Frank would lose a precious advantage. No, if possible, Joe had to keep his intrusion a secret.
    What if he jumped from the truck the next time it stopped for a traffic light? But the service window was shut. The only ways out were the two sliding doors in the front. Joe couldn’t imagine how he could slip out through one of them without being spotted.
    Joe took a deep breath. If he couldn’t sneak out, he would have to do it another way. At the next stop, he would creep up behind Gus, knock him out, and run. Gus would certainly know that someone had been in the truck, but he wouldn’t know who.
    From somewhere behind the truck came the insistent sound of a horn. Joe tried to ignore it.Then something clicked in his mind. The honking made a pattern: short-long-long-long. He knew that. It was Morse code for J—J for Joe? he wondered. Yes! Frank was right behind the truck, about to make a move.
    Joe braced his arms against the van wall and the side of the custard machine. The sound of the horn was moving up alongside the truck now. Gus leaned on his own horn. Tires squealed as the truck’s brakes locked in a panic stop. Joe had been expecting something along those lines. Even so, the shock pitched him forward. His head banged against the metal side of the custard machine.
    Dizzy, Joe surged forward toward the front of the truck. Gus was out on the street, shouting and shaking his fist. Frank had leaped out of the blue car, which was in front of the van, blocking its way.
    Joe, bent double, slipped out the right-hand door of the Freddy Frost truck and between two parked cars to the sidewalk. Once there, he straightened up and ran out into the street again, as if he were just arriving.
    â€œHi, Frank,” he called. “Any problem?”
    Frank shook his head. “Nothing we can’t handle,” he said.
    â€œGet that crate out of my way, or I’ll