A guild of cunning thieves sneaks their way into an opulent mansion, filled with the riches that only generations of power can acquire. The mansion's private guard patrol within, seeking out intruders and relentlessly hunting down those that their efforts reveal. Every shadow is a potential hiding spot, every noise might be a clue to the presence of thieves. Every second lost can mean the difference between victory and defeat.
"Latrodectus Gigas, or the Giant Widow Spider, is a rare but deadly species of spider. They general grow to be about the size of a large dog, although stories tell of Giant Widows the size of a horse. They can occasionally be encountered within cities, living off of rats, dogs, street urchin and other vermin. Their urban habitat of choice appears to be the sewers, in particular beneath the homes of the upper class, where they devour the vermin that are attracted to the rich bounty of food in the mansion above. For this reason their presence is usually tolerated. They also provide another layer of defence against the more human vermin who may seek entry to a mansion from below...
Some individuals in the upper class have even been known to keep Giant Widows as pets, living artwork or subjects in the advancement of Natural Philosophy.
Giant Widows anatomy is similar to a normal spider, with the following exceptions..."
-- Excerpt from Lord Baradine's "Species of the Cities"