Exhibit 10.21

THIRD LEASE AMENDMENT

THIS THIRD LEASE AMENDMENT (the “Amendment”) is executed this 21st day of April, 2010, by and between DUKE REALTY LIMITED PARTNERSHIP, an Indiana limited partnership d/b/a Duke Realty of Indiana Limited Partnership (“Landlord”), and INTERFACE SECURITY SYSTEMS, L.L.C., a Louisiana limited liability company (“Tenant”).

W I T N E S S E T H:

WHEREAS, Landlord and Tenant entered into a certain lease dated December 20, 2001, as amended March 18, 2002 and March 26, 2009 (collectively, the “Lease”), whereby Tenant leased from Landlord certain premises consisting of approximately 22,920 square feet of space (the “Leased Premises”) in a building commonly known as Corporate Center I, located at 3373 Corporate Center Drive, St. Louis, Missouri 63045; and

WHEREAS, Landlord and Tenant desire to extend the Lease Term; and

WHEREAS, Landlord and Tenant desire to amend certain provisions of the Lease to reflect such extension, changes and additions to the Lease.

NOW, THEREFORE, in consideration of the foregoing premises, the mutual covenants herein contained and each act performed hereunder by the parties, Landlord and Tenant hereby agree that the Lease is amended as follows:

1. Incorporation of Recitals. The above recitals are hereby incorporated into this Amendment as if fully set forth herein.

2. Extension of Lease Term. The Lease Term is hereby extended through June 30, 2010.

3. Amendment of Section 1.01. Basic Lease Provisions and Definitions. Commencing on May 1, 2010, Section 1.01 of the Lease is hereby amended by deleting subsections D, E, H and L and substituting the following in lieu thereof:

“D. Minimum Annual Rent:

May 1, 2010 - June 30, 2010

$53,480.00 (2 months);

E. Monthly Rental Installments:

May 1, 2010 - June 30, 2010

$26,740.00 per month;

H. Term: Through June 30, 2010;

L. Broker: Summit Realty Group LLC, d/b/a Gateway Commercial, representing Tenant;”

4. Amendment of Section 2.02. Construction of Tenant Improvements. Section 2.02 of the Lease is hereby amended by incorporating the following:

“Tenant hereby acknowledges that the Tenant Improvements designated as Landlord’s obligations in Exhibit B of the Lease have been completed in a satisfactory manner.”

5. Deletion of Section 2.05. Early Occupancy. Section 2.05 of the Lease is hereby deleted in its entirety and shall be of no further force or effect.

6. Broker. Tenant represents and warrants that, except for Duke Realty Services, LLC representing Landlord, and Summit Realty Group LLC, d/b/a Gateway Commercial, representing Tenant, no other real estate broker or brokers were involved in the negotiation and execution of this Amendment. Tenant shall indemnify Landlord and hold it harmless from any and all liability for the breach of any such representation and warranty on its part and shall pay any compensation to any other broker or person who may be deemed or held to be entitled thereto.

7. Representations and Warranties.

(a) Tenant hereby represents and warrants that (i) Tenant is duly organized, validly existing and in good standing (if applicable) in accordance with the laws of the State under which it was organized; (ii) Tenant is authorized to do business in the State where the Building is located; and (iii) the individual(s) executing and delivering this Amendment on behalf of Tenant has been properly authorized to do so, and such execution and delivery shall bind Tenant to its terms.

(b) Landlord hereby represents and warrants that (i) Landlord is duly organized, validly existing and in good standing (if applicable) in accordance with the laws of the State under which it was organized; (ii) Landlord is authorized to do business in the State where the Building is located; and (iii) the individual(s) executing and delivering this Amendment on behalf of Landlord has been properly authorized to do so, and such execution and delivery shall bind Landlord to its terms.

8. Examination of Amendment. Submission of this instrument for examination or signature to Tenant does not constitute a reservation or option, and it is not effective until execution by and delivery to both Landlord and Tenant.

9. Definitions. Except as otherwise provided herein, the capitalized terms used in this Amendment shall have the definitions set forth in the Lease.

10. Incorporation. This Amendment shall be incorporated into and made a part of the Lease, and all provisions of the Lease not expressly modified or amended hereby shall remain in full force and effect.

(SIGNATURES CONTAINED ON THE FOLLOWING PAGES)

IN WITNESS WHEREOF, the parties have caused this Amendment to be executed on the day and year first written above.

LANDLORD:

DUKE REALTY LIMITED PARTNERSHIP,
an Indiana limited partnership, d/b/a Duke Realty of Indiana Limited Partnership

By:	Duke Realty Corporation,
	its general partner


	By:	/s/ Thomas R. Martin
		Thomas R. Martin
		Senior Vice President
		St. Louis Group


TENANT:

INTERFACE SECURITY SYSTEMS, L.L.C., a Louisiana limited liability company

By:	/s/ Kenneth Obermeyer

Printed:	Kenneth Obermeyer

Title	CFO

(SIGNATURES CONTINUED ON THE FOLLOWING PAGE)

STATE OF Missouri	)
	) SS:
COUNTY OF St. Louis	)

Before me, a Notary Public in and for said County and State, personally appeared Kenneth Obermeyer, by me known and by me known to be the CFO of Interface Security Systems, L.L.C., a Louisiana limited liability company, who acknowledged the execution of the foregoing “Third Lease Amendment” on behalf of said limited liability company.

WITNESS my hand and Notarial Seal this 21st day of April, 2010.

	/s/ Lori A. Huck
	Notary Public


	Lori. A. Huck
	Printed Signature
My Commission Expires: Sept. 12, 2011


My County of Residence: St. Charles