my $critical_data = 'Original Value'; print "Begin: $critical_data\n"; &SubOne($critical_data); print "End: $critical_data\n"; sub SubOne { print "\tSubOne Got: @_\n"; &SubTwo; } sub SubTwo { print "\tSubTwo Got: @_\n"; $_[0] = 'pwned!'; } __END__ Begin: Original Value SubOne Got: Original Value SubTwo Got: Original Value End: pwned!