“Only what I explained,” Larry retorted. “I hadn’t thought about colored ice cubes, ever——”

“And aren’t you taking any hint from the yellow tones?” Sandy demanded.

“No! Why should I?”

“Don’t you, Dick?”

“Not a thing, Sandy. What’s in your mind?”

“Well—think! If they can freeze lemonade, and get yellow ice cubes, they can freeze lime juice—even something darker—and get——”

“Green cubes!” Larry broke in. “Yes—or freeze indigo and get blue ones. What of it?”

“What would dark green ice cubes conceal?”

Both chums stared at Sandy.

What would dark green ice cubes conceal?——