Monroe's injection gives H.G. excessive force but also turns him vicious without restraint while the serum effect lasts to turn on everyone. John now John was ready to side with good, he's cage, abused a guinea pig and left to die in a lab fire set by Wells to destroy the whole project. Monroe already fails to fool the military into believing his research is worth continuing and ends up burned himself. Wells returns by time machine and so does Jack, whose killer instincts are only sharpened by revenge, to which aim he joins Brooke, carrying a vile of the serum.
—KGF Vissers