This is a full spoiler summary, consider yourself warned
The Pale Blue Eye opens with Augustus Landor arriving at the United States Miltary Academy. After the body of Cadet Fry was found, Landor was summoned to solve a murder mystery. At first, it was believed that the cadet died of suicide by hanging, but after Landor questioned one of the guards on the night of the deed, along with an examination of the body, Landor has reached the conclusion that Cadet Fry was murdered. This case was also interesting, as Cadet Fry’s body sported a long vertical cut to remove his heart. Although the area around the heart was damaged, it is believed by the coroner that the heart was removed successfully.
Following this discovery, Captain Hitchcock gives Landor some ground rules surrounding this investigation. The odd rule was that Landor was to refrain from drinking. After returning to the scene of the crime, another cadet approaches Landor and reveals some information. According to the cadet, the murderer Landor is searching for is a poet. Landor then questions the guard on duty the night before. The information he discovers there is that an officer relieved the private, however, the request was odd and the bars on the officer’s left shoulder were missing.
After the day of investigating, Landor proceeds to break his rule of no drinking. At the bar, he meets Edgar Allan Poe, who is enrolled in the Academy and the same cadet that mentioned that the killer was a poet. After some small banter, Poe gives a lead to Landor to investigate a cadet named Loughborough, as he was Fry’s roommate before they had a falling out of unknown origins.
The next day, Landor confront Loughborough and reveals that Fry had fallen in with a “bad bunch”. However, Loughborough doesn’t know if the “bad bunch” refers to cadets or not. Loughborough assumes the former. Then, Landor questions Stoddard, as he was the last to see Fry alive. Although he doesn’t reveal much, Stoddard mentions that Fry was going to take care of “necessary business”. After Stoddard leaves, Hitchcock receives a note that mentions that a cow and sheep have been murdered and their hearts removed.
Landor then recruits Poe to his work. Landor wants Poe to decipher a note for him. Later that night, after reminiscing about the past, Poe reveals that the message was decoded. After some back and forth between the two characters, it was decided that Fry was on his way to meet a woman the night he died. According to Poe, he had a glimpse of this unknown woman as well.
The next day, Landor and Poe meet at the ice house. There, Landor reveals that the ice house is the location where Fry’s heart was brought. After, the two visit Professor Pépé, as there were symbols found in the ice house. Through a volume written by a man who killed many witches, the three things needed to achieve immortality are to eat unclean animals deemed by the Christian faith, the hearts of unbaptized children, and the hearts of hanged men.
After being excused from class, Poe is confronted by Marquis to meet him at 11 that night. On his way out to reach the rendezvous point, Poe is caught by Hitchcock and sent back to barracks. Also that night, Landor has visions of his daughter, which causes him to despair.
The next day, Landor attends Fry’s funeral. There, he is given a diary that belonged to Fry, as the strange lettering and numbering confused Fry’s mother. After the funeral, Landor meets Dr. Marquis’ wife Julia, who brings up uncomfortable details about Fry’s body and Landor’s past. That night, Poe is invited to the Marquis’ residence and hears Lea play. After some charming dialogue, the two set up a time to meet at a cemetery.
Ripping pages from Fry’s diary and dipping it in a liquid, Landor finds a message underneath all the messy writing. During this time, Poe accompanies Lea during their walk through the cemetery. After a heated discussion, Lea collapses due to a seizure. When she awakens, she is glad that Poe is there waiting for her.
That night, after a successful date, Ballinger attacks Poe for getting too personal with Lea. Landor then saves Poe from strangulation. The next day, Ballinger goes missing and the whole Academy begins a search for him. Eventually, he is found dead and hanging, with a cut on his chest, though the cuts are different, which suggest a different person did the deed. Landor is then confronted by the higherups, who question Landor’s allegiance, as Poe seems suspicious in their eyes.
It is then revealed that Poe knew of Fry. Landor then confronts Poe the next day, and more information is revealed. Although Poe did lie to Landor, Landor believes Poe about his innocence, but warns Poe about his words and actions.
That night, Poe and Landor join the Marquis for a family supper following Ballinger’s death, as Ballinger was family to them. After a tense meal, and while the family is distracted by Lea’s piano, Landor looks around the house. While snooping around, Poe is enthralled by Lea and confesses that he will do anything for Lea. After this confession, Landor soon finds something intriguing. It is the officer’s coat with the missing left bars. As Landor reveals this to the family, Hitchcock arrives to inform everyone present that another cadet ahs gone missing.
As Landor talks to Pépé about the witches, Poe reveals a dream he had with Lea that explained her illness. As Lea asks again if Poe would do anything for her, Landor confronts Dr. Marquis, who is a relative of Henri Le Clerc, who was a famous witch hunter until he became hunted. It is then revealed that Henri was in control from the grave through Lea.
In another location, Lea, Artemus, and Julia stand over Poe and commence a ritual to heal Lea. In Lea’s eyes, to save her from her illness, she must sacrifice Poe, whom she loves. As Artemus is about to stab Poe, Landor interrupts the ritual, which causes Lea to knock over some candles that set the room on fire. As Lea tries to continue the ritual, she is struck by the collapsing debris. Artemus moves to her side and the two are killed by the debris and fire. Through this interaction, it was revealed that Lea was the cause of all the death that occurred over the past month.
After Poe recovers from his ordeal, he meets with Landor. Poe reveals that he knows Landor’s daughter and that she had a role to play in the situation. Poe first reveals that the handwriting in Fry’s note and the note sent to Poe were of similar handwriting. It turns out Mattie, Landor’s daughter, was taken advantage of one night. Eventually, Mattie was unable to stand her pain anymore and jumped off a cliff. As a final twist, it turns out the first kill was made by Landor as revenge for what happened to his daughter. It was only because Lea and Artemus found a dead body that those two continued their own needs.
After all this, the truth was revealed. Landor had killed Fry. Then he was the one who killed the sheep and cows. Landor even killed Ballinger and cut his heart out. The only one who escaped his vindictive rampage was Stoddard. As a final wish, Landor wishes Poe met Mattie that fateful night instead.