Mr. Weaver spread the yellowed map of Beantown on his workbench.

"Kids," he said excitedly, "this map is over 100 years old, and it's written in code!"

"Wow, what could it mean?" said Willie as he peered over his dad's shoulder at the confusing jumble of faded letters. "How can we decipher this?"

"I know how!" announced Grace. "My brother Miguel is home for Thanksgiving. He is in the Navy, and his job is working with codes. Let's take this map to him."

So off went Grace and Willie to the Castillo home. Miguel was sitting at the computer with Furball curled up on his lap, purring loudly. Rosy, the cockatiel, chattered from her cage in the corner.

"Miguel, can you decipher this code for us?" asked Grace.

"Let's see it, Grace. Get off, Furball! I think this cat gets fatter everytime I come home. Well, this appears to be a simple substitution code."

"Can you crack it?" asked Willie eagerly.

"Sure I can. In fact, I have a special computer program that can decipher it for us in just a few minutes."

Miguel found the program, typed in the letters of the code, clicked the mouse a few times, and said, "That was easy!"

"What does it say? Tell us!"

And here is what the code said:

"Street named for a saint? A cat that ain't? That's as clear as mud!" wailed Grace.

"It wouldn't be a mystery if it weren't mysterious." Miguel always said things like that.

Suddenly Furball jumped up and stared intently at the window. He was twitching his tail the way cats do when they are spooked.

The three humans looked toward the window, but not in time to see the shadowy form slip away from the window and into the dark night...

NEXT STORY: "On the Waterfront"