Short version: Zafira's injuries from shadows rebounding on herself (see The Conclusion of the Whole Alastair Thing) begin to turn green. Magic spreads the process making her blood green, and Niccolo has to tamper with her true name to stop her magic from continuing to poison her. Deacon appears with a girl named Sparks at his side, asking to be healed, because he has also somehow contracted green blood, but by the time he arrives Niccolo has gone and no one is there to heal him. After some threats and arguments, Deacon and Sparks leave.
Long version: To be continued and whatnot.