print "Start: \$file = $file\n";
my($thebase) = ($file =~ /(.*)\/[^\/]+/);
print "  \$thebase = $thebase\n";

my($html,$html2);

print "Just before test to see if \$file exists\n";
if (!-e $file){
   print "$file does *NOT* exist!\n";
   $thebase =~ s/\/[^\/]+$/\/default/;
   print "\$thebase *AFTER* substituting default = $thebase\n";

    ### the rest of your code ###