The Blackthorn Key

Seven of Oswyn's men, including the Elephant and Martin, come out of the maze, heavily armed. Lord Ashcombe shoots one and the other six respond in turn. Two more King's Men are injured, and Christopher ducks down. One of Oswyn's men hits Lord Ashcombe in the arm. The other King's Men receive injuries. Lord Ashcombe continues to fight until he kills one of the boys and Wat strikes him in the hand, then the head, with an ax. Oswyn stops Wat before he can strike a third blow, because he doesn't want Lord Ashcombe to die yet. Christopher considers picking up a fallen sword, but Oswyn kicks it away.

Lord Ashcombe calls Oswyn a traitor, but Oswyn says it is Lord Ashcombe who is the traitor, and that he will kill the king and become the Lord Protector himself. Martin is seriously wounded and calling out for help; Oswyn gestures to the Elephant, who kills him. Oswyn then nods at Christopher, but he only wants the Elephant to search him. Wat confirms he killed Lord Ashcombe's soldiers in the maze, and that their bodies are still there. The Elephant discovers the sash on Christopher and gives it to Oswyn, who identifies the oil of vitriol as what ruined his lock. 

Christopher asks how Oswyn knew Lord Ashcombe would be waiting, and Oswyn replies that he's had a spy working for him. Therefore, he knew that Christopher had sent a letter to Lord Ashcombe even before he received his own letter. Oswyn wonders how Christopher figured out he was behind the murders. Christopher explains that he knew because of Wat, whom Oswyn claimed not to know but whom he clearly knew because he was allowed entrance into the Hall on a Sunday. This means that Wat is part of the Guild, and that Oswyn—having tested every apprentice—would have known him. Christopher deduced that Wat was Oswyn's apprentice. Oswyn admits that he wanted to kill Christopher. Now, he's glad that he didn't, because Christopher has information that he wants.

Oswyn demands the recipe for the Archangel's Fire. Christopher claims that his Master never told him about it and that he lied about it being in the puzzle cube, which Oswyn has already realized. Oswyn explains that when Christopher fled from the Hall, he didn't yet know that Oswyn was the murderer, so he must have had a mission. Now, Christopher has summoned him to Mortimer House, which Oswyn refuses to believe was by accident. 

Oswyn explains that he wants the fire to do good and get rid of the pleasure-loving king. Lord Ashcombe says he should have had him hanged. Oswyn supports Cromwell's revolution against the king, which Oswyn hopes to finish with the Archangel's Fire. Christopher responds angrily that all he truly wants is power, not good. Oswyn has Wat tie up Lord Ashcombe as he tries to get more information out of Christopher. The Elephant pins Christopher down, and Oswyn starts to drip oil of vitriol on his chest while asking him about the Fire. When he brings the oil up to Christopher's eyes, Christopher tells him.

Christopher goes down into the vault with Oswyn, Wat, and the Elephant, who carries Lord Ashcombe. Oswyn tells Christopher he wishes he'd chosen him as an apprentice. Oswyn and the other boys explore the workshop. Christopher directs them to the workbench, where Oswyn sends Wat. Meanwhile, Christopher ducks into the oven and pulls out the cylinder he made earlier. The Elephant punches him before he can do anything with it. Wat pries his fingers open, and the vial rolls away. 

Oswyn examines the cylinder, while Christopher begs him not to light it, claiming it is the Archangel's Fire. Oswyn has Wat light it in the testing room. As he does, Christopher goes over to Lord Ashcombe and has him get up. The cylinder explodes, throwing Wat across the room and unbalancing the Elephant. The flames die down, and Oswyn is impressed, thanking Christopher. Christopher gestures secretly to Lord Ashcombe, looking at the oven. The Elephant notices that the ceiling is on fire. The flames have caught four canon fuses there and are spreading toward cylinders. Christopher pulls Lord Ashcombe into the oven just before the room explodes.

Christopher awakens to the sound of Master Benedict's voice telling him to get up, though he fights it. He opens his eyes with a bad headache and a ringing head. He pulls a sharp stone out of his arm. Around him, the room is in ruins; Lord Ashcombe is there, still breathing. Christopher struggles to stand up, noticing that Oswyn and the Elephant are gone. Wat is there, injured by still alive. Wobbly, he gets to his feet with a knife in his hand. He approaches Christopher but before he can hurt him, Tom appears and hits Wat on the head with a rolling pin.

Christopher climbs the ladder, Tom carrying Lord Ashcombe behind him. They stop a carriage and Lord Ashcombe commands it to go to the Tower. There, he falls unconscious and the King's Men take Christopher to a room alone for a long time before someone comes for him. He is led to a set of luxurious rooms, where doctors will help him in a while. Christopher asks about Tom, but the man tells him that Lord Ashcombe only asked for Christopher. Christopher sits down to eat and starts crying.

Three days later, Christopher finally got to see Lord Ashcombe in the Tower. Christopher apologizes for his trap, but Lord Ashcombe (now missing an eye) is impressed by how he used the Archangel's Fire. Lord Ashcombe wonders why Christopher let Oswyn torture him first. Christopher explains that he didn't want to seem like he was giving up the secrets too easily. 

After their conversation, Christopher stays in the Tower for two more weeks as Lord Ashcombe investigates the plot and finds many people in high places connected with it. Those involved are punished in the public square; Christopher is allowed to watch, but he doesn't. Christopher wants to see Tom and Bridget but is otherwise happy to stay in the Tower. 

Finally, Christopher is released and immediately summoned to the Apothecary's Hall, even though it is a Sunday. He appears in front of Sir Edward and Valentine Grey. Sir Edward tells Christopher they are awarding him ten pounds for having been treated badly and will purchase a new apprenticeship for him in another guild. Christopher is upset, because he only wants to be an apothecary, but the Guild members do not want him after all of the recent events. As they cannot find his will, which Christopher believes Oswyn stole, Master Benedict's shop will belong to the Guild.

Lord Ashcombe and Isaac show up to argue on Christopher's behalf. On behalf of the king, Lord Ashcombe calls Christopher a friend and expresses his hope that Christopher's new master will manage his property well. This confuses the Guild until Isaac presents them with Master Benedict's will, leaving everything to Christopher. As it is witnessed, and the king is willing to uphold it, the will is valid. The king will act as ward and pay a salary to the new master. 

Tom meets Christopher outside the Hall, as Isaac sent him a message. Lord Ashcombe and Isaac approach them, and Lord Ashcombe gives the puzzle cube back to Christopher, who thanks him for everything. Lord Ashcombe tells him not to be too grateful, because some people will dislike him for his alliance with the king. Isaac pulls Christopher aside to tell him that they buried Master Benedict but should have a private service and that they can meet tomorrow. Back with Lord Ashcombe, Christopher wonders if Oswyn's men are still around; Lord Ashcombe tells him such men always are, and that the King's Men lost Wat, who probably left the city. 

Lord Ashcombe tells Christopher that his men have not found the recipe for the Archangel's Fire. Christopher says it was on the workbench and may have been destroyed, but Lord Ashcombe remembers Wat saying he couldn't find it there. Lord Ashcombe asks Christopher to keep him updated, then offers Tom a chance to train as a soldier at the Tower. 

Back at the apothecary shop, Tom challenges the story that Christopher told Lord Ashcombe about the recipe. Christopher tells him that he actually hid it in the ice vault, behind some bricks. Despite the fire, it might still be there. They clean up the shop as Christopher hopes to save as much as possible, thinking of Master Benedict. Bridget appears at the window and Christopher lets her in, cuddling her and silently thanking his master.