SEC Filing | Evergy, Inc.

Filed by Great Plains Energy Incorporated Pursuant

To Rule 425 Under the Securities Act of 1933

And Deemed Filed Pursuant to Rule 14a-6

Under the Securities Exchange Act of 1934

Subject Company: Aquila, Inc.

Commission File No.: 333-142715

This filing consists of the following letter distributed to Great Plains Energy Incorporated stockholders commencing on October 2, 2007:

GREAT PLAINS ENERGY INCORPORATED

Kansas City, MO 64106

Dear Great Plains Stockholder:

According to our latest records, we have not yet received your proxy for the important Special Meeting of Great Plains Energy to be held on October 10, 2007. Your Board of Directors has unanimously recommended that stockholders vote FOR the issuance of shares of common stock in connection with our acquisition of Aquila, Inc.

Please help your company avoid the expense of further solicitation by voting TODAY— by telephone, via the Internet, or by signing, dating and returning the enclosed proxy card in the envelope provided.

Thank you for your cooperation.

Senior Vice President—Corporate Services and

REMEMBER:

You can vote your shares by telephone, or via the Internet.

Please follow the easy instructions on the enclosed proxy card.

If you have any questions, or need assistance in voting

your shares, please call our proxy solicitor,

INNISFREE M&A INCORPORATED

TOLL-FREE, at 1-877-687-1871.

Additional Information and Where to Find It

In connection with the acquisition of Aquila by Great Plains Energy, Great Plains Energy filed with the SEC a registration statement on Form S−4 (Registration No. 333−142715), containing a definitive joint proxy statement/prospectus and other relevant materials. INVESTORS AND SECURITY HOLDERS OF GREAT PLAINS ENERGY AND AQUILA ARE URGED TO READ THE DEFINITIVE JOINT PROXY STATEMENT/PROSPECTUS AND THE OTHER RELEVANT MATERIALS BECAUSE THEY CONTAIN IMPORTANT INFORMATION ABOUT GREAT PLAINS ENERGY, AQUILA AND THE ACQUISITION. The registration statement, definitive joint proxy statement/prospectus, other relevant materials and any other documents filed by Great Plains Energy or Aquila with the SEC may be obtained free of charge at the SEC’s web site at www.sec.gov. In addition, investors and security holders may obtain free copies of the documents filed with the SEC by Great Plains Energy by directing a request to: Great Plains Energy, 1201 Walnut, Kansas City, MO 64106, Attn: Investor Relations. Investors and security holders may obtain free copies of the documents filed with the SEC by Aquila by contacting Aquila, 20 West Ninth Street, Kansas City, MO 64105, Attn: Investor Relations.