主人公加西莫多是流浪的吉卜西（赛）人的弃儿，生来就畸形：独眼、驼背、跛足。吉卜西人偷偷地拿他换走了雷姆地方一个妇女的小女儿阿涅。巴黎圣母院的副主教克罗德收养了加西莫多，在成年后让他在圣母院里当敲钟人。由于长年敲钟，他的耳朵又震聋了。加西莫多忠于职务，对副主教极为崇敬，唯命是从。
一个节日的晚上，副主教指使加西莫多去抢吉卜西少女爱斯梅哈尔达，被国王卫队撞上，队长法比救下少女。次日加西莫多被判了刑，在格雷勿方场鼓台下被鞭打示众。加西莫多痛苦万分，要求喝水。副主教看见后悄悄溜走，吉卜西少女却大胆地送水给受刑的加西莫多喝。可怜的敲钟人从此对她感激不尽。
原来吉卜西少女正是被流浪人偷走的阿涅。她年轻、美丽，能歌善舞。节日晚上被卫队长法比救下来以后就爱上了他，约定相会。这事被副主教得知，跟踪法比，藏在他们幽会的地方，并在法比和爱斯梅哈尔达互诉爱慕时，用匕首刺伤法比，自己溜走。吓昏过去的爱斯梅哈尔达被逮捕，法庭控诉她以妖术谋害国王侍卫的罪名，又用酷刑逼她认罪，从而判处她绞刑。在狱中副主教一再向爱斯梅哈尔达表示，只要她肯爱他就能免死。但少女坚定地爱着法比，副主教恼羞成怒，宣布执行绞刑。行刑的前一天，爱斯梅哈尔达跪在圣母院门前执行忏悔仪式。突然，加西莫多冲出来抱起少女跨进圣母院的门槛，高喊：“圣地!”卫队、狱卒和围观的人群都不敢行动，因为根据当时的宗教法规，凡在教堂内的人都应受到上帝保护，即使犯了死罪，也不得逮捕。加西莫多把爱斯梅哈尔达藏在最高塔楼的小房间里，拿自己的食物、被褥送给她，每夜守卫在她的房门口，对她百般爱护。不久副主教找到了这个藏身之地，夜间潜入室内，想强奸少女，被守卫的加西莫多发现未遂。
流浪人得知爱斯梅哈尔达被无理判处死刑，都非常愤怒，他们各自武装起来，一路冲向法院，一路包围巴黎圣母院。但热爱吉卜西女郎的加西莫多，因为是聋子，误以为他们是来追捕她的敌人，在教堂顶上抛下用来修理房屋的各种建筑材料，造成流浪人的大量伤亡。国王路易十一虽然不喜欢宗教势力，但又惧怕人民起来，派出军队去镇压。
副主教趁机骗走爱斯梅哈尔达，把她拖到鼓台前，逼她选择：或者上绞台，或者答应爱他。少女卑视他，宁死不屈。副主教把她拖到“老鼠洞”前，叫修女居第尔抓住她，自己跑去喊卫队。
修女居第尔其实就是少女的母亲。她在失去小女儿以后，带着留下的一只绣花小鞋跑遍各地寻找，在绝望的情况下皈依宗教，进了活棺材——“老鼠洞”，当了修女。当爱斯梅哈尔达看到那只小鞋时，她也拿出装在自己护身符里的一只同样的绣花小鞋，于是母女相会。修女砸断铁窗栏，把失去了十六年的女儿藏进“老鼠洞”，母女俩沉浸在骨肉团聚的欢乐里。这时被副主教喊来的监狱长和卫队包围了“老鼠洞”。母爱使居第尔产生了力量和智慧，她骗过了他们，使他们相信吉卜西少女已经逃走。但是当爱斯梅哈尔达听到法比的名字时，忍不住冲出窗口，暴露了自己。于是母女被带到刑场，女儿上绞架，母亲惨死在绞架下面。
最后，加西莫多看透了副主教的丑恶灵魂，把他从塔楼上推下去摔死后，找到爱斯梅哈尔达的尸体，紧紧地抱住它死去。
小说通过副主教的卑劣行为，非常有力地揭露了宗教的残酷和虚伪。是束缚人性的宗教使他的爱情变成可怕的欲望，害了别人，自己也得不到好下场。作品还以加西莫多外形的丑来对照他内心的美。吉卜西少女爱斯梅哈尔达是作者理想的化身，在她身上体现了雨果心目中最崇高的感情和最美的形象。
Notre Dame cathedral " describes is one beauty, is romantic but the again pitiful love story. Is lost abandoned by the parents humpbacked Karsy are not many, in one accidental situation by vice- Bishop Klode - the trust Rollo adoption is the adopted son, grows after lets it works as Notre Dame cathedral strike a gong again the person. West gal not many although the appearance is extremely ugly moreover has the many kinds of deformity, actually throughout maintains one nobleness, chaste heart. The elder roams about the street corner gypsy girl Chinese mugwort Lare reaches can the song friendly dance, naive appearance America moreover the heart is sincere. The very poor young poet you - the Gansu fruit tile accidentally meets one another compared to Egypt with her, and synthesized in her name husband in one accidental field. Very has the fame vice- Bishop Klode - trust Rollo, originally one to wholly absorbed to " saint duty ", but suddenly one day, he appreciates to the gypsy girl's dance, lit in his heart buries already fire the long desire. Thereupon, he by any means possible wants the Chinese mugwort Lare to reach appropriates to oneself, posed all sorts of threats to her even frames, simultaneously also did not hesitate to play with means, deceived and uses him the adopted son Karsy are not many and student Gan Guo Wa. At the same time, passes on the armed escort Chief Philippine Beese although has had the sweet and pretty fiancee actually loose purports because of the natural disposition to bribe the Chinese mugwort Lare reaches. The Chinese mugwort Lare reached falls in love Philippine Beese, this caused the trust Rollo unusual envious hatred, he took advantage of when the Chinese mugwort Lare reached with the Philippine Beese lover's rendezvous, stabbed Philippine Beese then shifts blame for the Chinese mugwort Lare reaches, coerces her by the body little, otherwise had to execute her. But, the Chinese mugwort Lare reached rejects. Shortly in any event also realized does not hold the evil attempt which the Chinese mugwort Lare reached, trust Rollo finally unexpectedly personally the lovable young girl delivers the death by hanging frame. On the other hand, Karsy are not many also admires the beautiful Chinese mugwort in private Lare reaches, but because of feels inferior but deeply buries this love in the heart. Sees girl encounters frames, west the gal not multipurpose Scheme rescued her, and let her seek asylum in the notre dame one secret room. Strikes a gong the person comforts her with extremely simple and the sincere sentiment, protects her. Soon gypsy person's leader gram Low Pan leads the audiences to attack the notre dame, the intention rescues the Chinese mugwort Lare reaches. The Philippine Beese leadership armed escort routed the gypsy person. Knows oneself the incapable resistance army Karsy not thinks Philippine Beese is rescues the girl, then let trust Rollo Lare reach the Chinese mugwort gives the Philippines Beese. Has not thought of Philippine Beese because does not dare to enrage the fiancee again announces Lare reaches the Chinese mugwort executes. When inside the grief and indignation Karsy not many accidentally discovers oneself " adoptive father " and " benefactor " far looks high hangs when sends out devil in the death by hanging above gypsy girl grin fiendishly, he understands all. Karsy were not many to that hypocrisy gets down the final decision, and personally from in the clock tower which reached to the sky pushes down trust Rollo, causes it to fall meets a cruel death. Even if so, Karsy not many also does not have can save the spouse the life, he begged executioner's agreement to hold the remains which the Chinese mugwort Lare reached, hid Lare reaches in in the Paris public cemetery cave with the Chinese mugwort together changes into the dust which the life and death relied on one another
Spitz: An experienced and clever Husky, Spitz is the original lead dog of Buck's dogsled team. He fears and hates Buck, whom he sees as a rival. He is eventually killed by Buck in a fight for leadership.
Curly: A sweet Newfoundland dog, one of Buck's first companions after he has been kidnapped. She is unexpected killed for trying to make friendly advances toward another dog.
Dave: Another one of Buck's first companions, he is one of the most knowledgeable dogs on the team. Mostly aloof, new life springs into him the moment he is placed in a harness. Not only does he help teach Buck the procedures, he also embodies pride in his work.
Sol-leks: Another member of the team. Like Dave, he is aloof until attached to a sled. At first only wary of being approached on his blind-side, poor treatment makes Sol-Leks more and more unfriendly.
Billie: Another member of the team. He is good-natured and sweet, and he shows Buck how to make a bed in the snow. He is killed by Hal.
Joe: Another member of the team, Billie's brother. Unlike Billie, Joe is always snarling and defensive.
Pike: Another member of the team, often referred to as "the malingerer." He rarely gets up on time, and he will steal food and generally undermine the expedition. When Buck becomes leader, he forces Pike to shape up and become a helpful member of the team.
Dub: Another member of the team. He is an awkward blunderer who gets blamed for Buck's thievery.
Dolly: Another member of the team, Dolly goes mad after being bitten by wild huskies, tries to attack Buck, and is killed by Francois.
Skeet: A motherly Irish setter who belongs to John Thornton. She nurses Buck through his recovery and engages him in play.
Nig: A huge black dog who belongs to John Thornton. He has laughing eyes and a good nature.
Lone wolf: The "wild brother" that Buck meets in the forest. He understands Buck's wild nature.
Judge Miller: Buck's original owner. He is presumably a sedate and prosperous man with a large family.
Manuel: The gardener's helper on Judge Miller's estate. He kidnaps and sells Buck to fund his gambling habit.
Red sweater: Also known as the man with the club. He metes out discipline to all dogs that will be sold for sledding. Ruthless in his repeated beatings of unruly creatures such as Buck, he maintains composure and control. He does not beat out of cruelty, it seems. Rather, he looks to teach these dogs the lessons that will allow them to survive in this harsh environment. Buck never forgets the law of the club.
Francois: A Canadian Frenchman, the original dogsled driver. He is knowledgeable and understanding of his dogs, but still very strict.
Perrault: Francois's superior and an agent of the Canadian government. He is admired by Buck for his fearlessness in blazing their trail, disregarding the threat of ice that might break.
Hal: A young man of nineteen or twenty who purchases Buck and his team once they have used up their usefulness to the government. He has ambitions to find gold, but his incompetence and laziness are out of place in the harsh environment. He has no understanding of the dogs, and mistreats them terribly.
Charles: Hal's brother-in-law, a weak figure who does not say much. He basically follows Hal around and does what he is told.
Mercedes: Sister of Hal, wife of Charles. She is exceedingly self-centered, and spends most of her time crying and complaining.
John Thornton: The man who rescues Buck from Hal's cruelty. He is by far the most admirable human character in the story, kind but full of the uncompromising strength that is necessary to survive on the trail. John is the ideal master because his nature is so dog-like.
Pete: One of John Thornton's partners.
Hans: One of John Thornton's partners.
"Black" Burton: A notorious troublemaker, he picks a fight in a bar and John Thornton steps in.
Matthewson: The man who bets John that Buck cannot pull a ton of weight.
Jim O'Brien: The man who loans John the money to make the bet against Matthewson.
Yeehats: The group of Valley Indians that raids the camp of John Thornton and his companions and kills them. They are terrorized when Buck returns and kills most of them. From then on they speak of a dog inhabited by the devil that roams the forest.