When you put on a mask and fight for what's right, secrets are your stock and trade. They protect you, and those around you, from those that would seek to end your quest for justice. But when those secrets are compromised, the shield can become a sword in the hands of a vengeful enemy. What will happen when that moment comes for our heroes? When the mask slips, just a little? And what fury will come crashing through The Hidden Door?
A symposium in the city has the world's greatest scientific minds together under one roof. A fine opportunity to advance mankind's knowledge - and perhaps a target too tempting to resist! But with that masked mystery man The Red Panda, the fearless fighting female The Flying Squirrel and their army of agents on the case, the conference is safe from any threat in the world. But what about... The World Next Door?