777 is correct! You’ve cracked the case!
Open the envelope!
Transcript of audio file:
Bill once told me, "Kid, you'll never answer one big question and crack a case. It's always the little things, added together, that break a case open." And looking back, there were lots of little things. Why were there no signs of a break-in? Makes sense now, huh? How did the thief know my hat was still new and creased? He'd been looking at it everyday. The typewriter to write the clues? Mine. On my desk. In his office. Bill's also taller than a toddler, that's a big one. But he has two of them at home. Also answers why this thief never felt like a criminal. I have half a mind to turn him in anyway, that would teach him. Ah... I guess it could be worse. Least now I can finish that sandwich. (meow) Hmm. Case number two solved, too. I'm on a roll.

