Kaitou's devious game becomes a fight for survival as Hiei, Botan, and Kuwabara all fail prey to the twisted teen's bizarre rules. But Kurama issues a challenge...one by one the letters of the alphabet will become taboo. If any of the taboo sounds are uttered, the speaker will face a terrible penalty. Placing his own soul on the line, Kurama prepares himself to battle wits with the brilliant Kaitou.

Kuwabara and the gang finally reach the room where Yusuke is being held captive. But Kido has one final game to play with the Spirit Detective. One of his friends is in fact an imposter, and Yusuke has only minutes to determine which one it is! With his decision made, Yusuke attacks!

A tunnel is being carved between the Living World and the Demon World that if completed would usher in such darkness and chaos that the world might never recover. In a bold move, the despicable Sensui begins his search for the person that will finally allow him to complete the tunnel.

Somewhere in Mushiyori City, a psychic is forging a tunnel between the Demon and Human worlds. Yusuke has recruited Murota, a mind-reading human. But while trying to weed out the enemies by their thoughts, Murota was shot -- and the criminal mastermind made his introduction. The heroes have taken Murota to the hospital, where new danger awaits.

Searching Mushiyori City, Yusuke's team was quickly steered to the hospital, where a trap awaited. There they encounter the Doctor, a human with immense psychic powers, super strength, feels no pain, and has infected the entire hospital with a deadly virus. To save his friends, will Yusuke be forced to destroy the wretched creature?

As Sensui's plan continues, Kuwabara and his friends attend a rock concert. However, they are ambushed by Sensui's next minion: Seaman, a person with the ability to create monsters out of water. With his friends held hostage, Kuwabara must battle Seaman alone...

Kuwabara's battle with Seaman continues.

Shinobu Sensui, the former Spirit Detective, is revealed to be the mastermind behind the plot to remove the barrier to Makai. Koemna discusses his fall into insanity with Yusuke's group.

Sensui makes his appearance, and battles Yusuke, Kuwabara, and Kurama. Sensui's abilities enable him to battle all three on equal footing. During the battle, Sensui manages to kidnap Kuwabara.

As Yusuke continues his chase of Sensui, the unbelievable Sniper confronts Yusuke. As Genkai and the rest of the team follow, can Yusuke escape Sniper's endless barrage, reach Sensui and save Kuwabara... not to mention, the entire human race?

Yusuke continues to evade Sniper's dangerous attacks, but the horrible villain may still have a few tricks up his sleeve. Meanwhile, Hiei has finally returned to his former teammates to join in their crusade, but will that be enough to free Kuwabara before Gourmet can consume his power, and tear the Kekkai Barrier to shreds?

Yusuke, Kurama, Hiei, and Mitarai enter a cavern controlled by the tricky Gamemaster. Gamemaster's territory can be manipulated into a video game, a game where everyone must play by the rules in order to survive. Yusuke's team must win 4 rounds to move on, but is a victory possible against an adversary who can manipulate the rules?

Yusuke's team has won the first round, but they'll need to win three more to defeat the Game Master and move on to Sensui's lair. The hole to the Demon World is rapidly expanding. Can they make it there in time to prevent the end of the world?

Only two hours remain before the tunnel opens unleashing a horde of hungry demons upon the world of the living. Kurama steps forth to battle Gamemaster for the right to move on to Sensui's lair and Yusuke senses that one of them will not make it out alive.

Yusuke and his entourage have made it to Sensui's lair, but their battle to save the human race is just beginning. The opening to the Demon World is widening rapidly and shows no signs of slowing down. What's more, an old nemesis reveals his own master plan. His target, Kurama!

Kurama's anger has sentenced Toguro to an eternity of suffering, forever chasing his foiled revenge. But the tunnel to Demon World is opening. Can Yusuke's team still save the human race? Only a dramatic showdown between the past and present Spirit Detectives will reveal the truth!

As the epic battle between Yusuke and Sensui continues, Yusuke learns that he is no match for the former Spirit Detective. As Sensui prepares the finishing blow, aid comes in a most unexpected package. And what is the truth behind Sensui's unique personalities?

As Itsuki explains more about the bizarre Sensui, Koenma prepares to use his most powerful weapon: his pacifier! It can create a barrier that would stop the demons from flooding Living World. Koenma knows that Sensui must be stopped or his evil plan will come to fruition dooming the entire human race!

Koenma's tactics have saved Yusuke for now. But mysteriously Yusuke won't allow the Prince of Spirit World to use his pacifier. While they discuss their next move, the terrible gateway between Demon World and Living World opens.

Yusuke comes to terms with the fact that he cannot defeat Sensui. Watching but unable to help, Kuwabara fights off emotion with rage as he remembers all the good times and bad he's had with his best friend. Kuwabara manages to free Kurama and Hiei, but it's too late. Yusuke Urameshi has been destroyed.

Too late to save their friend's life, Kuwabara, Kurama, and Hiei unleash their most devastating attacks on Sensui, who retreats within the tunnel. King Yama reveals a dark secret to Botan. What news would cause her to tremble in terror? What does King Yama know about Yusuke that the others do not?

With no thought to their own safety, Kuwabara, Kurama, and Hiei charge deep into the tunnel in an effort to rid all worlds of Sensui forever. Meanwhile, King Yama's soldiers arrive to take Yusuke's body away to ensure he is never revived. As Koenma does his best to stop them, help arrives on the horizon in a very different form.

After being saved in the nick of time by Puu, Yusuke revels in his new power and resumes his battle with Sensui. Although Yusuke's skill and strength have increased, he is still clumsy with his new abilities. But there is no time to practice as Sensui bears down for the final confrontation.

Yusuke's body has undergone an intense transformation as his dormant demon blood takes hold. As the battle against Sensui concludes, Koenma tells Yusuke that he must choose between Demon World and Living World. Without hesitation, Yusuke makes his decision!

Yusuke and team return topside to the waiting arms of their friends. But all is not well. King Yama's soldiers arrive saying that they must destroy Yusuke once and for all. Could this be the end? How much energy does the Spirit Detective have after his exhausting battle with Sensui?