Four-Way Lookups Possible?

[perfectview]

I've need to lookup a date thats buried in data four levels deep, but wonder if it's even possible, anyone know how to prove me wrong and has a solution?

My monthly spreadsheets structure is as follows:
Within multiple companies (column A), there are numerous departments (column B), within these departments are various roles (column C), and each role was last filled on 'X' date (column D); I need to show when there are differences to the dates between two files for any given role between two months.

Hence a lookup, but array/non-array, I only know how to do a two-way lookup (non-array preffered). This problem already has my desk buried in four levels! Thank you in advance.

[shg]

A sample workbook with an explanation and example in context?