At the hospital, Grandma leaves Conor to enter his mother’s room on his own. His stomach feels sour; he has never been pulled out of school before, not even when his mother was hospitalized last Easter. He ignores the questions racing through his mind. His mother is awake and smiling, but Conor notices the fear behind her smile. He feels himself starting to get very angry. He slumps in a chair instead of sitting on her bed. She says she wanted to see him. He says, “This is the talk, isn’t it?” She says the yew tree treatment isn’t working and she has an infection. Conor realizes there aren’t any more treatments. She says she’s never been more sorry about anything in her life.
Conor grows angry at her for having said she believed the treatment would work. She says she did believe, and that believing is what kept her there so long. Conor says she lied. She says that deep in his heart, he’s always known, hasn’t he? She says it’s okay that he is angry; if he needs to break things, he ought to. He nods. She lets out a long sigh of relief and says she’ll need more painkillers. She presses the button to administer the medication and goes to sleep. Grandma enters. Conor says he wants to go home—to his home, the one with the yew tree.
Grandma drops Conor at the house and says she is going back to the hospital; she’ll be back in an hour to get him to have dinner at the hospital. Conor says there’s something he has to do. The house smells of dust and stale air. He goes through the house, climbs the back gate, crosses the train tracks, and goes to kick the yew tree awake. The monster steps to the side. Conor shouts that the yew tree didn’t heal her. He asks what the use of the tree is if it can’t heal her. The monster says it did not come to heal her; it came to heal Conor. Conor says he doesn’t need healing, it’s his mother who is...but he can’t complete the sentence. Even though he has known it all along, he can’t say it. Conor cries furiously and asks the monster to help him. The monster says it is time for the fourth tale, and opens its hand: mist surrounds them, and they are in the middle of the nightmare.
Terror seeps into Conor. His stomach begins to fall. He is in the cold darkness that followed ever since his mother had first been hospitalized. Conor refuses to tell the tale. He says he has to get his mother. The monster says she is already here. The monster drops Conor from his hand into the grey clearing, which is bordered by forest on three sides and a cliff on the fourth with blackness beyond. His mother is on the cliff’s edge. Conor tells her to run, but she says she is fine. A low rumbling sound comes from below the cliff. The "real monster" is climbing up the cliff. Conor’s mother turns to him but he knows it is too late. Conor pushes against the invisible weight holding him down and tries to reach her as the booming grows louder. Two fists made of black cloud grab her, pulling her over the edge. Conor throws himself toward her and catches her hands.
He tries to keep her from being pulled down into the blackness. He sees the real monster: it is formed of cloud and ash and dark flames, but it has red eyes and real muscles. The real monster pulls harder and Conor’s mother screams in terror for Conor to hold on to her. She becomes impossibly heavy. The yew monster tells Conor that here is the fourth tale: the truth of Conor O’Malley. Conor refuses to speak the truth. Then his mother falls. This is the moment when he usually wakes up. But he stays in the nightmare with the yew tree. The monster says he let her go; she is no longer here. Conor says it is just a nightmare, it isn’t the truth. The monster says it is: he let her go. Conor insists she fell, but the monster says again that he let her go. Mist rises, filling Conor’s lungs and coiling like tendrils around his legs. The monster says Conor will be trapped there forever if he can’t admit the truth.
The monster says, in a kinder voice, that he let her go: he could have held on forever, but he loosened his grip and let the nightmare take her. He wanted her to fall. He demands that Conor say why he let her go. The truth burns inside Conor. Finally, he tells the rest of the fourth tale. He admits that he can’t stand it anymore. He can’t stand knowing that she’ll go. He just wants it over, he wants it to be finished. The fire eats the world, wiping away everything and him away with it. Conor welcomes the relief because it is, at last, the punishment he deserves.
Conor opens his eyes. He is lying on the grass hill above his house, still alive. He tells the monster that he has known forever that his mother wasn’t going to make it. He never believed her when she said she was getting better. He cries as he says he couldn’t stand how it made him feel to know she was going to die. The monster says a part of him wished it would end, even if it meant losing her. The monster repeats that the truth was that Conor could have held on, but he let her go. Conor says he didn’t mean to. He says now she’s going to die and it is his fault. The monster says that isn’t the truth at all.
Conor is gripped with grief. The monster says he was merely wishing for the end of the pain that kept Conor isolated; even though Conor meant it, he didn’t mean it. The monster says humans are complicated beasts. A queen can be a good witch and a bad witch. A prince can be a murderer and a savior. An apothecary can be evil-tempered and right-thinking. A parson can be wrong-thinking but good-hearted. Invisible men can make themselves more lonely by being seen. The monster says Conor’s mind will contradict itself a hundred times a day: it will believe in comforting lies while also knowing the painful truths that make those lies necessary. The monster tells Conor that you do not write life with words, but with actions. The painful truth was just a thought, not an action. Conor feels very tired. The monster makes a nest of leaves and branches and promises he will be there with Conor to visit his mother.
Conor wakes up on the hill by his house to his Grandma’s voice thanking God that she has found him. She runs over and hugs him, which surprises her. She pulls him back to the car and he doesn’t ask why they are hurrying. As she speeds, Conor quietly apologizes. She says it doesn’t matter. She says they aren’t the most natural fit, but they’ll have to learn. Conor says he knows. With tears streaming from her eyes, Grandma says they have one thing in common: Conor’s mother. They hurry into the hospital. The nurse says it’s okay; they arrived in time. The room is dark aside from a light cast over Conor’s mother’s bed. Her eyes are closed and she breathes as though there is a weight on her chest. She reaches out her hand to Conor. He thinks of his dream and hears the monster behind him say, “Here is the end of the tale.”
Conor asks the monster what he should do. The monster holds his shoulders and says all Conor has to do is tell the truth, however afraid he is. The monster gently but firmly guides Conor’s hands toward his mother. Conor sees the clock above her bed display "11:46 p.monster."—twenty-one minutes until 12:07. Conor feels like he knows what is going to happen. Conor takes his mother’s hand. She opens her eyes briefly. Conor knows he is going to get through it. It will be beyond terrible, but he’ll survive. The monster assures Conor he will stay and says all he has to do is speak his truth. At last Conor tells his mother he doesn’t want her to go. In a heavy voice, she says she knows. He leans forward and holds her. He repeats that he doesn’t want her to go. Conor knows her death will come soon, maybe even at 12:07. She will slip from his grasp no matter how tightly he holds on. But not this moment, the monster whispers. The novel ends with Conor holding tightly onto his mother, and by doing so, the narrator comments, he can finally let her go.
In the novel’s last chapters, Ness depicts Conor’s mother finally deciding to break with the optimistic pretense she and Conor have been upholding and admit to Conor that she will not get better. Still steeped in his denial, Conor angrily rejects her attempt to connect with him and accuses her of lying about ever having believed she would survive. Conor’s mother calmly explains that the belief wasn’t a lie, but something that genuinely kept her alive that long. Simultaneously, she has known that the treatments wouldn’t be successful, and she gently suggests to Conor that he too has known all along—that he too has occupied the same state of cognitive dissonance.
Despite the conversation, Conor still cannot accept the truth of what’s happening. He expends the last of his anger by confronting the yew tree, seeking to blame the monster for not healing his mother. The monster reveals that he has come walking not to heal Conor’s mother but Conor himself. Conor responds by insisting he doesn’t need healing, but he cannot utter the words “cancer” or “dying” in relation to his mother—evidence of how Conor’s denial has kept him from even naming the phenomena that have been determining his life.
Saying it is time for the fourth tale, the monster takes Conor directly into the territory of his nightmare. Ness reveals that the “real monster” Conor has feared throughout the book is a haunting mass of dark black cloud who pulls Conor’s mother over the edge of a cliff as Conor grasps her arms. The dream has overt allegorical resonance with Conor’s life situation, as the real monster represents the cancer that has been slowly killing his mother, and Conor’s mother's effort to hold on to her is analogous to Conor’s efforts to uphold the pretense that she will get better.
The shame-generating truth contained in the dream is that Conor knows he could hold on to his mother’s arms longer but he lets go and feels some relief to let her fall. Conor finally admits his truth to the monster: he can’t stand to watch her die and he just wants the ordeal to be over. Having admitted this, a fire burns away the world of the nightmare and Conor feels relieved to be engulfed in oblivion, believing the world has ended and that this is the punishment he deserves. However, a moment later Conor realizes the world hasn’t disappeared: he is in the calm environment of his yard with the monster.
The monster interprets Conor’s nightmare as an allegory for how Conor has been holding on to his mother’s life. Conor says that because he let go of her in the dream, she will now die, and so it his fault. The monster says that isn’t the truth. Bringing in the lessons from the first three tales, the monster impresses upon Conor the idea that he, like other humans, is a complicated being. Because of cognitive dissonance, the mind can hold on to inconsistent and seemingly contradictory beliefs: Conor can at once believe in the comforting lie that his mother will get better and yet know the painful truth that makes the lie necessary.
To bring the fourth tale to a conclusion, the monster accompanies Conor to the hospital in the novel’s final chapter. With the monster’s help, Conor is able to finally admit his truth to his mother. Despite what Conor’s dream might suggest, the truth he speaks to her is not that he wants her to die so that he can find relief from the pain of watching her die, but the deeper truth that he doesn’t want her to go. Until now, he has thought it was his responsibility to pretend he believed she was going to heal. Because of this denial, Conor hasn’t been able to admit to her that he doesn’t want her to go, as the admission would break the illusion that she was going to get better. Having finally accepted and shared the truth of his feelings, Conor comes out of his denial and isolation. By saying goodbye to his mother properly, Conor can begin to grieve and heal as he lets her go.