Fantomcat centres on the character Phillipe Lentheric Guerlain de Givenchy, the Duke of Fantom, a masked swashbuckling hero who thrived in 1699, in mortal combat with his nemesis Baron Von Skeltar (a sword-wielding caped Skeletoid alchemist). De Fantom was treacherously cast into a painting within the halls of his house, Castle De Fantom, and became trapped for centuries. As time passed, the area around Castle De Fantom became a bustling metropolis called Metro City, a city submerged in crime rings led by the fiendish arachnid Marmagora.