The A Vow So Bold And Deadly starts with Rhen who has been delaying making decisions for the war since he doesn’t want to in the first place and is only doing it because Lilith, the enchantress is alive and is blackmailing him as usual, but no one in the castle knows that, not even Harper.
The castle has been distant from Harper, and so has Rhen since she helped Grey escape and now, the only one who is not at odds with her is Zo, who is her friend and even helped Haper save Grey, but it cost her her position from the royal guard.
One day at the day of a party, Prince Rhen arranged to win the numerous court’s favour, and he also gains a spy to send in syhl shallow.
Harper and Rhen finally clear all their misunderstanding, and Rhen tells her about Lilith’s return which he had been hiding for weeks, if not months.
Harper gets shocked and informs the guards without even listening to her, and they get taken back to Ruen’s chamber to talk, but Lilith comes there and gets quite shaken up by Harper, and the guards also see proof of her return.
Meanwhile, the soldiers in syhl shallow still don’t trust Grey or the others from ember fall. They think Lia Mara a weak queen for having a man standing by her side, but they are still training hard, and Grey also trains privately with Lisak the Scraver to improve his magic which he is kind of getting the hang of but of course, when something happens, he always takes his sword first.
While answering some of her people’s requests and worries, Lia Mara gets attacked and the culprit uses science but says that magic would be her downfall and everything goes up in flames which also burns Lia Mara and they all go back to her chambers where then Grey heals her but it is a big thing for someone to attack the queen in front of everyone then run.
The attack was meant to serve as a warning that magic will be their downfall, and even though she used science, many people still thought that it was magic even though Noah, the doctor, kept telling them.
Later Lia Mara gets attacked again in her own chambers, but luckily Grey was there, and he stopped the attempt, but it was clear that someone was trying to kill the queen and it also made Lia Mara very anxious, and she often got scared of every little thing thinking that it is another assassination attempt.
They all later found out that there is a whole rebellion that is going on against magic, and they also research Magesmiths and things related to it.
Back in ember fall, Rhen stations guards at the border since Syhl shallow has also kept some of their guards on their side of it.
Lilith also gives Harper a little visit and warns her of her power and also almost suffocates Harper. Harper asks the guard commander Dustan not to tell Rhen about her visit, but he still does, and Rhen is not happy and goes to being cold with Harper again, but he also hires Zo again as a guard but this time not for him but for her since he knows that the castle has still not completely forgiven Harper and that if the time comes, they will not kill themselves for her but Zo would.
Their party was heading over to Silvermoon which is a town nearby whose grand general had agreed to lend his help, and with them goes the new spy that Rhen had hired. She brought a dagger that works against magic, and Rhen buys it of her for a fortune, and no one knows that he intends to use it against Lilith and not entirely on Grey for the war.
They decide into a group of two.
One being Rhen and all the rest of the guards he brought with him and the other being Harper and Zo who have decided not to go with them.
They find out that it was a trap and all the citizens of Silvermoon had come and circled Rhen and the guards that he brought along and there are enough rebelling citizens that they almost throw the guard over and then Rhen has to make a decision, and he was almost about to cut their grand general’s head on the spot to make an example out of him but Harper comes along with Zom and she tries to get to Rhen but the citizens overwhelm her and she injured her ankle.
Rhen gets to her and he is even able to have all the commoners to go because of the dangerous vibe he was giving off.
They go back to the castle though it doesn’t feel like a retreat and once there, Harper manages to convince Rhen for a truce so they can have peace and not war, but Lilith comes, and she is not in a good mood.
Lilith kills most of the occupants in the castle, which ends up in the corridors being filled with bodies and blood all along their walls, and she even injures Rhen a lot which makes him also unable to use one of his eyes possible forever.
Rhen tells Harper to run, which she doesn’t do at first, choosing to try instead to attack Lilith, but after watching the enchantress RIP out the guard commander Dustan’s throat, Zo drags Harper outside.
They get on a horse, but from above comes a creature, and it drags Zo off the horse.
Harper makes a stop at the inn that they had once stayed in, then she starts moving towards syhl shallow to try to get their help since the only one that can face Lilith’s magic is Grey meanwhile, Lilith tells Rhen that Harper is dead showing a heart to prove.
In syhl shallow, there are only a few days left until they set out to battle when they get news that a woman has arrived claiming that she is princess Harper.
They lock Harper up and several days pass until first comes her brother Jake then she is finally able to see Grey and Lia Mara.
At first, they think that she is here seeking sanctuary after the prince got injured and she can’t return even though a lot of people were wary of her then they finally understand that she wants their help for rescue and immediately everybody starts thinking that it’s a trial meant to lure them to their deaths only days before the war except the ones who are from ember fall including Grey, Tycho, Jake, Noah and also Lia Mara who just likes to think the best of people and Harper also meets Lisak who she tells them looks like the creature that dragged Zo off the horse they were trying to escape on.
No one is too happy to go to Rhen’s rescue, but it is possible that after Lilith takes over ember fall, she will attack syhl shallow. Hence, the soldiers set out towards Emberfall, being led by Grey who also had the dagger that works against Magesmiths from Harper who brought the dagger along with her and with him were also ten soldiers, including jake, Tycho and captain solt, who didn’t get along with Grey very well but was getting better and Harper to work as a guide.
The soldiers still think that this is a trap but still go on nonetheless.
When they enter ember fall, they get attacked by the guards that were stationed at the border, but Grey uses his magic to knock them all out, and the spy was among them who they surprisingly recognise as someone quite close to the court and captain Solt puts a sword through her chest even though she was already dead by being shot twice in her chest by arrows and they move on.
Back in Syhl shallow, Lia Mara gets a message that the forces were attacked, but they got out with limited casualties and that the spy was dead.
Lia Mara also decided that they are gonna go after them and once again try for peace with prince Rhen if this a trap or not, and they also take Noah.
Rhen gets informed that there are soldiers coming for war with him by Lilith and at this point, he doesn’t really care but once again he is blackmailed by the enchantress who said that she will also kill the remaining soldiers that are left alive so Rhen takes his sword and goes outside where he nearly stumbles upon Grey.
The party Grey brought with him had decided into three since there were guards on either side of the castle one being led by captain Solt while the other one is being led by Jake who had become Grey’s right-hand man and Grey was the one who was charging straight to the castle with Harper and Tycho.
As soon as Jake sees Grey he remembers that Harper wanted peace and he wields.
They go back to his chambers where Grey tries to heal Rhen’s face but it does leave scars then Likith comes again and they fight.
Lilith is still more powerful and Grey doesn’t get to use the dagger that can work against magic properly until she takes it then suddenly from the window, Lisak comes and deals a fair amount of blows before Lilith stabs him multiple times then she gets hold of Rhen.
Grey turns Rhen back into the monster since it can hurt Lilith and as a monster, Rhen rips Lilith apart in pieces and she finally dies but they couldn’t save Lisak and he dies too.
Outside in the courtyard, they go to see Lisak’s son pinned down by an arrow and he was the one who attacked Harper and the one who Lisak had been looking for years so Grey heals him but he says that he cannot trust any more Mega Smiths and flys off.
Lia Mara and the rest of her party arrive to find that they had already won and everything is returned to normal and some of them the castle occupants had escaped and were now back including Zo who wasn’t killed by Lisak’s son.