"The occasion is that you're coming on a mountain hike with us, out in the nice fresh air and sunshine!" Sandy informed him. "And please don't argue," Phyl said with a giggle. "It's for your own good--not to mention ours." "I suppose Chow Winkler put you up to this." Tom grinned. "Never mind that," Sandy said sternly. "Just come along quietly. It's a beautiful day." Tom glanced at his workbench cluttered with drawings and electronic gear. "Well, okay, since you're twisting my arm," he agreed. "I guess it might clear my brain at that." "Now you're talking." Bud clapped Tom on the back and propelled him toward the two girls, who promptly seized his arms before he might change his mind. On their way to the door, however, the telephone rang. Tom insisted upon answering it, in spite of the girls' scolding. "Tom Swift Jr. talking." "This is Chief Slater, Tom," said the voice at the other end of the line. "Dimitri Mirov wants to see you. I don't know what's up, but he might be ready to tell something worth while. Could you drop by?" "Sure thing, Chief. Right away!" Tom hung up, excited by the thought that the Brungarian might be about to reveal an important secret. "Mind stopping by police headquarters first?" he asked his friends. Minutes later, Bud's red convertible pulled up in front of the gray stone building. Tom jumped out and dashed up the granite steps. "I've had Mirov transferred to a cell by himself," Chief Slater said as he took Tom back to see him. "Figured he might talk more freely away from his pals." The prisoner, however, showed no eagerness to do so at Tom's arrival. He remained slouched on his bunk as the young inventor pulled a chair up to the cell bars. His only response was a slight curl of the lips. "Have you heard about my country's new submarine?" Mirov inquired after Chief Slater left. Tom nodded curtly. "When are _you_ going to build one?" Mirov prodded slyly. "Look!" Tom snapped. "You asked to see me. Here I am. What is it you want?" Mirov shrugged with a look of amusement. "To make a bargain with you," he replied casually. "I know the secret of that sub. Get me and my friends released and I'll give it to you." Tom had no intention of doing so, but he parried the offer, hoping to draw Mirov out further. The prisoner, however, would say nothing more. At last Tom gave up and rose to leave. "I'll think over your proposition," he said. He heard Mirov chuckle as he walked away. Somewhat puzzled, Tom reported the conversation to Chief Slater and also telephoned the plant to inform Ames. Then he hurried back to the car. Bud frowned upon hearing Tom's story. "Do you think he's on the level?" Tom shrugged as they headed out into the countryside. "I may be wrong, but the whole thing sounded fishy."