good idea.
a super villain kidnaps Edna Mode to design him/her a costume with added powers/accessories making him indestructible, but when she refuses he threatens to kill E and Edna signals the incredibles with a homing device, and they come and have to sneak in to the lair, but get caught, atleast not jack-jack and violet who go invisible and find all the guards and kill them then free family and go find E, get into battle with villain defeats him/her, rescues edna, then somehow incorporate underminer at the end.