DOES FORCE ACT ON CHARGE IN CENTRE OF mETAL SHELL?

q CHARGE IS PLACED IN CENTRE OF A METAL CONDUCTOR SHELL. ANOTHER TEST CHARGE q' IS PLACED OUTSIDE THE SHELL. WHAT FORCE DOES q' EXERT ON q . IF IT DOES EXERT FORCE THEN WHY DONT LINES OF FORCE REACH INSIDE CONDUCTOR, IF NOT THEN WHY??? IS COLUMB'S LAW INVALID IN THIS CASE