Mary and Alice continue their sisterly bonding, Ryan, Luke and Sophie are desperate and willing to do almost anything to stop them…even entertaining a dangerous proposition by Renee Montoya that finally rid Gotham of Pamela Isley. As the team hunts for the source of Poison Mary's power – and potential demise – Renee is forced to revisit her heartbreaking past. Meanwhile, Marquis grows more unhinged and throws a spectacularly sinister soiree at Wayne Tower…and everyone is invited.