Penny Nichols Finds a Clue

Penny Nichols flung open the office door of the Nichols Detective Agency, descending upon a dignified, gray-haired man who was busy at his desk.
Dad, she announced, I've come to report a mysterious disappearance!
Christopher Nichols dropped the correspondence upon which he was working and regarded his daughter for a moment, his gray eyes flashing an indulgent welcome.
What sort of disappearance? he inquired cautiously.
Penny laughed as she opened her purse, disclosing an empty coin container.
It seems to be my allowance again. Yesterday I had two dollars. Now the old pocketbook is as bare as Mother Hubbard's cupboard!
Mr. Nichols' chief interest in life centered about his charming young daughter and he found it hard at times to keep from pampering her. It was especially difficult at this very moment as Penny stood there, her blue eyes twinkling mischievously, her full red lips parted in an enticing smile, and a few unruly ringlets of curly golden hair framing her forehead in an artistry both casual and becoming.
Now that is a most bewildering case, he agreed with mock seriousness. I don't suppose that rattle-trap roadster of yours might offer a clue to the mystery?
I'm afraid it does, Penny admitted. Only this time I indulged in seat covers instead of spare parts. As a result I'm flat broke. And I'm to meet Susan Altman at the tennis courts in ten minutes.
Mr. Nichols smiled indulgently as he reached into his pocket for a roll of bills.
I'll come to the rescue this time, young lady, but mind, I'm charging it up to next week's allowance.