I need help with the following:

On Sheet 1, I have a list of about 100 employees: A= Last Name, B=First
name, C= (blank).

On sheet 2, I have a list of all employees (40,000+) broken up in 3 columns:
A=employee ID, B= Last Name, C= First Name

I want to make a function in cell C4 of sheet 1 that would pull the employee
ID from sheet 2. I am trying to avoid searching one by one.

Can anyone help???