find matching value and return data from previous column

attached is an example
i want to return the location from the matching PO number from sheet 2. So A1 in sheet 1 would return ATL


I dont know if this can be done and I have exhausted my efforts trying!

I have 2 spreadsheets:
in the 1st spreadsheet, I want to find the value in column D off the 2nd speadsheet from column I and return the value from a previous column (A)

example
1st spreadsheet

a b c d e f g
1 = ? 554
2
3

2nd spreadsheet
a b c d ... I
1 atl 554
2
3

so in column A of the 1st spreadsheet, i want to take 554 and find it in the 2nd spreadsheet, then return 'atl' as the result.

does this make sense ... is it possible?