Gem Devourer

Jasper and Peridot were ordered by yellow diamond that they keep a prisoner known as "the gem devourer"(mordante) on their ship however, they don't know how much danger that their going to be in with having this new prisoner on their ship afterwards things go from bad to worse mordonate ends up on earth causing for sky blue topaz and black diamond to deal with what Peridot and jasper couldn't handle with the help of some gems and half gem.