$string =~ s/^\("(.*)"\)$/$1/;

##</code><code>##

# Faster than first.
$string =~ s/^\("//;
$string =~ s/"\)$//;

##</code><code>##

# Same as previous, less redundant.
s/^\("//, s/"\)$// for $string;

##</code><code>##

# You didn't mention an escape mechanism, so I'm
# assuming there's no other quotes in the string.
$string =~ s/"//g;

##</code><code>##

# I didn't say it was impossible.
$string = (split '"', $string)[1];