Not sure, why you are trying to use an indirect function here..
The 3rd parameter of the HLookup function can be replaced with the cell address where you have used the indirect function.
Your current formula :
=HLOOKUP(B2,Details!$E$14:$E$28,INDIRECT(Sheet2!$A$3,0),FALSE)
Formula can be written as:
=HLOOKUP($B$2,Details!$E$14:$E$25,$A$3,0)
In the above formula, the cell $A$3 has been given as the 3rd parameter for HLookup function.
Please let me know, if I understood your requirement in a wrong way