Hicks Acquisition Company I, Inc. 100 Crescent Court, Suite 1200 Dallas, Texas 75201 Fax: (214 ###-###-#### September 9, 2009

Exhibit 2.1

Hicks Acquisition Company I, Inc.

100 Crescent Court, Suite 1200
Dallas, Texas 75201
Fax: (214 ###-###-####

September 9, 2009

Resolute Holdings, LLC
Resolute Holdings Sub, LLC
Attn: James M. Piccone
1675 Broadway St.
Denver, Colorado 80202

     Re: Purchase and IPO Reorganization Agreement

     Reference is made to that certain Purchase and IPO Reorganization Agreement (the “Acquisition Agreement”), dated as of August 2, 2009, by and among Hicks Acquisition Company I, Inc. (“Buyer”), Resolute Holdings, LLC, Resolute Holdings Sub, LLC (“Seller”), Resolute Aneth, LLC, Resolute Energy Corporation (“IPO Corp.”), Resolute Subsidiary Corporation (“Merger Sub”), and HH-HACI, L.P. (“Founder”). Capitalized terms used herein and not otherwise defined have the meanings assigned to them in the Acquisition Agreement. The undersigned hereby agree as follows:

     Neither Seller nor Buyer shall exercise their rights under Section 9.1(a)(iv) of the Acquisition Agreement at any time prior to October 6, 2009 if the Buyer Stockholder Approval shall have been obtained and the Charter Amendment shall have become effective and in such case, the parties won’t exercise their rights under Section 9.1(a)(iv) of the Acquisition Agreement unless the Closing shall not have occurred by October 6, 2009.

     Notwithstanding Sections 1.5(b), 1.5(c) and 1.6(b) of the Acquisition Agreement requiring (i) the cancellation and forfeiture of 7,335,000 shares of Buyer Common Stock and 4,600,000 Founder’s Warrants held by Founder and (ii) the restriction of 1,865,000 shares of IPO Corp. Common Stock receivable in the Merger in exchange for 1,865,000 shares of Buyer Common Stock held by Founder, the parties hereto hereby acknowledge and agree that such cancellation and forfeiture and such restriction shall be allocated pro rata among Founder and each of Buyer’s independent directors, as reflected on Schedule I hereto.

     The parties hereto acknowledge and agree that except as modified herein, the Acquisition Agreement remains in full force and effect. Please acknowledge your agreement to these terms by signing and returning this letter to the undersigned at the address listed above.

Agreed to and Acknowledged:
RESOLUTE ENERGY CORPORATION						RESOLUTE SUBSIDIARY CORPORATION
By:		/s/ James M. Piccone				By:		/s/ James M. Piccone
Name:		James M. Piccone				Name:		James M. Piccone
Title:		President				Title:		President
Date:		9/9/09				Date:		9/9/09
RESOLUTE ANETH, LLC						RESOLUTE HOLDINGS SUB, LLC
By:		/s/ James M. Piccone				By:		/s/ James M. Piccone
Name:		James M. Piccone				Name:		James M. Piccone
Title:		President				Title:		President
Date:		9/9/09				Date:		9/9/09
RESOLUTE HOLDINGS, LLC
By:		/s/ James M. Piccone
Name:		James M. Piccone
Title:		President
Date:		9/9/09

HH-HACI, L.P.
By:		HH-HACI GP LLC, its general partner
By:		/s/ Joseph B. Armes
Name:		Joseph B. Armes
Title:
Date:		9/9/09

Agreed to and Acknowledged, Solely with Respect
to Sections 1.5(b), 1.5(c) and 1.6(b) of the
Acquisition Agreement, as modified by this Letter:

/s/ William H. Cunningham

William H. Cunningham

/s/ William A. Montgomery

William A. Montgomery

/s/ Brian Mulroney

Brian Mulroney

/s/ William F. Quinn

William F. Quinn

Purchase and IPO Reorganization Agreement
Letter Agreement
Signature Page

Schedule I

		Forfeited Common Stock and Warrants / Earnout Shares
		Pre-Closing				Forfeited								Pre-Closing				Forfeited
		Buyer				Buyer Common				Earnout Shares				Founder's				Founder’s
Holder		Common Stock				Stock								Warrants				Warrants
HH-HACI, L.P.			13,524,000				7,188,300				1,827,700				13,524,000				4,508,000
William H. Cunningham			69,000				36,675				9,325				69,000				23,000
William A. Montgomery			69,000				36,675				9,325				69,000				23,000
Brian Mulroney			69,000				36,675				9,325				69,000				23,000
William F. Quinn			69,000				36,675				9,325				69,000				23,000
Total			13,800,000				7,335,000				1,865,000				13,800,000				4,600,000

		Pre and Post-Closing Ownership in Resolute Energy Corporation (“IPO Corp.”)
		Pre-Closing								Post-Closing1
		Buyer				Buyer				IPO Corp.				IPO Corp.				IPO Corp.
Holder		Common Stock				Founder’s Warrants				Common Stock				Earnout Shares				Founders Warrants
HH-HACI, L.P.			13,524,000				13,524,000				4,508,000				1,827,700				9,016,000
William H. Cunningham			69,000				69,000				23,000				9,325				46,000
William A. Montgomery			69,000				69,000				23,000				9,325				46,000
Brian Mulroney			69,000				69,000				23,000				9,325				46,000
William F. Quinn			69,000				69,000				23,000				9,325				46,000