Quelques mois après Hôtel Transylvanie 2, tous les membres de la famille de Dracula et ses amis se réunissent pour partir en vacances à bord d'un luxueux bateau de croisière. Pendant la croisière, Dracula tombe amoureux du capitaine qui n'est autre que la descendante du professeur Van Helsing, le tristement célèbre tueur de monstres.
A short time after the first film, Mavis (Selena Gomez) and her fiance Johnny (Andy Samberg) are married, with the approval of her father Dracula (Adam Sandler) and the world has become aware of (and unfased by) the existence of monsters. Mavis later reveals to Drac that she is pregnant and a year later, she gives birth to a son named Dennis (Asher Blinkoff), who befriends Wayne's werewolf pup daughter Winnie (Sadie Sandler). Nearing his fifth birthday, Dennis has yet to grow his fangs and Drac worries that his grandson might not gain vampire powers. Noticing the dangers of Transylvania, Mavis starts to consider raising Dennis where Johnny grew up, much to Drac's disapproval.
In the aftermath of the death of Dracula's wife Martha (Jackie Sandler) at the hands of an angry mob, Count Dracula (Adam Sandler) designs and builds a massive five-star hotel in Transylvania in which to raise his daughter Mavis (Selena Gomez) and to serve as a getaway for all the world's monsters.
In 1887, Transylvanian Doctor Victor Frankenstein brings to life his Monster with the aid of his assistant Igor and Count Dracula. After Dracula betrays and kills Doctor Frankenstein, the Monster escapes to a windmill, which is burned down by a pursuing mob. The mob flees as Dracula and his three brides mourn the loss of the Monster.
In the Middle Ages, Vlad Tepes (Luke Evans) is the Prince of Wallachia and Transylvania. As a child, he was a princely hostage of the Ottoman Empire and was trained to be a soldier in the Sultan's elite Janissary corps, where he became their most feared warrior. He was called Vlad the Impaler after slaughtering thousands by impaling them on spears. Eventually sickened by his acts, he put aside his past and returned to rule his domains in peace. One day in the forest, Vlad and his soldiers discover a helmet in a stream. Fearing that an Ottoman scouting party is preparing the way for invasion, they follow the stream to a high mountain cave called Broken Tooth Mountain. Upon entering the cave, they discover the ground of the cave is carpeted in crushed bone; and they are attacked in the dark by an unknown creature (Charles Dance) with shining red eyes, as well as inhuman speed and strength. While his men are killed, Vlad cuts the creature of the cave with his sword before being thrown to the ground. The blood on the sword he used to cut the creature dissolves when exposed to sunlight, and the creature does not pursue Vlad into the sunlight at the mouth of the cave. Returning to his castle, Vlad learns from a local monk that the creature is a vampire, who was once a man who summoned a demon from the depths of hell and made a pact with it for dark powers before being tricked by the demon and cursed to remain in the cave forever until he is released by someone who drinks his blood, then drinks the blood of a human. The person is welcome to share his power in exchange for the freedom to escape the cave.
In 1462, Vlad Dracula, a member of the Order of the Dragon, returns from a victory against the Turks to find his wife, Elisabeta, has committed suicide after receiving a false report of his death. Enraged that his wife is now damned for committing suicide, Dracula desecrates his chapel and renounces God, declaring that he will rise from the grave to avenge Elisabeta with all the powers of darkness. In a fit of rage, he stabs the chapel's stone cross with his sword and drinks the blood which pours out of it.
A group of vampires look for the hidden resting place of Drake, also known as Dracula—the genetic "father" of their species. They find him in a Syrian ziggurat tomb, although not before, in a moment of blood lust, he kills one of them. The vampires capitalize on Blade's reputation as a serial killer and frame him for the killing of a familiar. During the ensuing manhunt, the FBI locate Blade's latest hideout, and, during the siege, Abraham Whistler dies. With his mentor gone and surrounded by human authorities, Blade allows himself to be captured and arrested.
Matthew Van Helsing (Christopher Plummer), the alleged descendant of the famed 19th century Dutch medical doctor, Abraham Van Helsing, owns an antique shop in London in 2000. One night with Van Helsing upstairs, his secretary, Solina (Jennifer Esposito), allows a group of thieves (Danny Masterson, Lochlyn Munro, Sean Patrick Thomas), led by her boyfriend, Marcus (Omar Epps), into the shop. The thieves infiltrate the shop's underground high-security vault and find a sealed silver coffin protected by a deadly defense system. Based on the level of security surrounding the coffin, Solina and Marcus decide that the coffin’s contents must be valuable, so they escape with it and flee to New Orleans, Louisiana. When Van Helsing discovers that the coffin has been stolen, he boards a plane to America, telling his apprentice, Simon Sheppard (Jonny Lee Miller), to remain in London. Simon does not follow his mentor’s orders and travels to Louisiana as well.
The infamous vampire Count Dracula is expelled from his castle by the Communist government of Romania, which plans to convert the structure into a training facility for gymnasts (the head trainer declares that it will include Nadia Comăneci). The world-weary Count travels to New York City with his bug-eating manservant, Renfield, and establishes himself in a hotel, but only after a mix-up at the airport causes his coffin to be accidentally sent to be the centerpiece in a funeral at a black church in Harlem. While Dracula learns that America contains such wonders as blood banks, he also proceeds to suffer the general ego-crushing that comes from modern life in the Big Apple as he romantically pursues flaky fashion model Cindy Sondheim, whom he has admired from afar and believes to be the current reincarnation of his true love (an earlier being named Mina Harker).
In Whitby, England in 1913, Count Dracula (Frank Langella) arrives from Transylvania via the ship Demeter one stormy night. A sickly Mina Van Helsing (Jan Francis), who is visiting her friend Lucy Seward (Kate Nelligan), discovers Dracula's body after his ship has run aground. The Count visits Mina and her friends at the household of Lucy's father, Dr. Jack Seward (Donald Pleasence), whose clifftop mansion also serves as the local asylum. At dinner, he proves to be a charming guest and leaves a strong impression on the hosts, Lucy especially. Less charmed by this handsome Romanian count is Jonathan Harker (Trevor Eve), Lucy's fiancé.
The year is 1893: solicitor Thomas Renfield travels all the way from London to "Castle Dracula" in Transylvania to finalize Count Dracula's purchase of Carfax Abbey in England. As the sun sets, and the stagecoach driver refuses to take him any further, Renfield continues on foot despite the villagers pleading with him to turn back.
In 1921, German director Frederich Wilhelm Murnau takes his cast and crew on-location in Czechoslovakia to shoot Nosferatu, an unauthorized version of Bram Stoker's novel Dracula. Murnau keeps his team in the dark about their schedule and the actor playing the vampire Count Orlok. It is left to the film's other main actor, Gustav von Wangenheim, to explain that the lead is an obscure German theater performer named Max Schreck, who is a character actor. To involve himself fully in his role, Schreck will only appear amongst the cast and crew in makeup, and will never break character.
Lawrence Talbot (Lon Chaney, Jr.) is making an urgent call from London to a Florida railway station where Chick Young (Bud Abbott) and Wilbur Grey (Lou Costello) work as baggage clerks. Wilbur answers the phone and Talbot tries to impart to him the danger of a shipment due to arrive for the "McDougal House Of Horrors" (a local wax museum) which purportedly contains the actual bodies of Count Dracula (Béla Lugosi) and the Frankenstein Monster (Glenn Strange). However, before he is able to warn Wilbur, a full moon rises and Talbot transforms into a werewolf, who proceeds to destroy his apartment while Wilbur is on the line. Wilbur, thinking the call is just a prank, hangs up and continues on with his work day. Immediately thereafter, the actual Mr. McDougal (Frank Ferguson) shows up to claim the shipments and, fearing them damaged when Wilbur and Chick mishandle them, demands that the crates be delivered in person so his insurance agent can inspect them.
The Monster Squad is a society of young pre-teens who idolize classic monsters and monster movies and hold their meetings in a tree clubhouse. Club leader Sean (Andre Gower), whose five-year-old sister Phoebe (Ashley Bank) desperately wants to join the club, is given the diary of legendary monster hunter Dr. Abraham Van Helsing (Jack Gwillim), but his excitement abates when he finds it is written in German. Sean, his best friend Patrick (Robby Kiger), and the rest of the Monster Squad visit an elderly man, known as the "Scary German Guy" (Leonardo Cimino), actually a kind gentleman, to translate the diary. When the Monster Squad wonders how the German man is so knowledgeable about Van Helsing's battle with monsters, he wryly comments that "he has some experience with monsters" and his shirt sleeve briefly reveals a Concentration camp number tattoo.
In May 1885, Jonathan Harker arrives at the castle of Count Dracula near Klausenburg (Cluj), to take up his post as librarian. Inside, he is startled by a young woman who claims she is a prisoner and begs for his help. Dracula then appears to greet Harker and guide him to his room, where he locks him in. Jonathan starts to write in his diary, and his true intentions are revealed: he is a vampire hunter and has come to kill Dracula.