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Hot Line is the twenty-sixth episode of the Dr. Stone anime, and the second episode of the second season.


Chrome, Gen, and Magma make their way to the Tsukasa Empire in order to deliver the cell phone and get in contact with their spies, Taiju and Yuzuriha. Homura pursues them; however, Senku has a plan in mind to get her off their backs.

After capturing Homura, the cell phone team is free to reach the Tsukasa empire and hide the cell phone in a safe place: Senku's grave.

Plot Details[]

As Magma, Gen and Chrome leave the village, Magma complains that it'd be easier if they simply captured or killed Homura rather than attempted to sneak out. To that point, Chrome snaps that if they knew her location, they'd have done that first. Gen details that the Tsukasa Empire's main concern is gunpowder and the explosions from the detonated sonic bombs would force Homura to investigate. From the observatory, Suika spots Homura and quickly Kohaku sets off to capture her.

Senku capture Homura

Immediately after Homura arrives at the spot where the bombs were detonated, Kohaku ambushes her but Homura reflexively dodges the move. Kohaku gives chase but can't catch up to Homura whose flexibility and speed are a product of years of gymnastics training. Pursued by Kohaku, Homura refuses to give in and plans to exhaust her pursuer by keeping her talking and draining her energy but it doesn't work. The pursuit leads the two closer and closer to the village, and the villagers are ordered by Kokuyo to take shelter. It's then that Senku intercepts the two and uses his newest invention, the flash grenade to blind Homura.

Senku then captures the dazed Homura, but a moment later, she escapes due to Senku's weak hold and returns to safety. There, she scans the villagers and discovers that Magma, Chrome, and Gen are missing, and that this was a distraction. She flees, trying to catch up with the missing group.

With Homura gone, Chalk is tasked with trying to track her scent but is unable to do so. The villagers are concerned about the consequences of Homura finding their team but Senku reveals another new invention of his to help track Homura: a blacklight.

Black Light Road Map

Using powdered scheelite that he secretly covered Homura with, Senku uses his new invention to shine ultraviolet light on Homura's path, showing glowing spots on the snow and branches. As the pursuit group follow Homura's tracks, Kohaku asks if, given the opportunity, should she kill Homura. Senku replies that she shouldn't have to with their new communication device and sends a short ring to the other team to warn them that Homura's following them.

While camping overnight underneath a small cavity on the side of a hill, Senku explains to Kohaku and Kinro about how they'll perform a pincer attack against the unsuspecting Homura. Meanwhile, as dawn starts to break, Homura sitting atop a tree notices the scheelite glitter placed on her and the tracks she left from it. She washes it off in a small river, making it impossible for Senku's group to track her anymore. Gen also sends Morse code to Senku's group detailing their current location. Cross-referencing this new information, it's suspected that Homura has already caught up to Gen's group and is tailing them.

Homura captured again

After sunrise, and when Senku's group is almost caught up to Homura and the phone team, they execute the pincer attack. Homura is led to the top of a dead tree with a decoy of the phone's coil and aerial. Senku's team then shows up and Magma and Kinro chop the tree down, causing Homura to lose her grip and fall. She believed she was about to die but her life was by Kohaku who caught her.

With Homura recaptured, Gen's group continues towards the empire. Once the group reaches their destination, they find a large pile of petrified statues with numbers written on their foreheads. The lowest number written on the statues is 33, and Gen deduces that at least 32 people have been revived by Tsukasa. Magma produces the rational idea to break the arms and legs of the statues to make them incapable of fighting or being revived. Right as Magma was prepared to damage a statue, Gen stopped him. Understanding how savage Tsukasa is, Gen considers himself weak for being unable to kill or allow someone to kill other humans. Chrome then speaks in defense of Gen, claiming he's not weak and that their goal is one of a higher purpose.

By dusk, the group reach Senku's grave, and bury the cell phone under the grave marker. When trying to break a rock in the way, Magma makes a loud noise that draws the attention of Ukyo whose astute hearing picks up the sound and rushes to find the source of the noise.

The following day, Senku waits for Taiju and Yuzuriha's call. Eventually, he receives it.








Inventions and Discoveries[]

  • Flash Bulb
  • Blacklight
    • Wood's glass

Anime to Manga differences[]

  • Extra scenes of the cell phone team transporting the device are shown such as them sliding down a snowbank and them eating the instant ramen from the previous episode.
  • While in the manga, the cell phone's ringing sound seems to be a loud hissing "KZZZZZT" sound (similar to a walkie talkie), the anime switched it to a more traditional electric bell.[1]


  • The flash lamp used in the flash grenade is single-use as the bright light is produced by the magnesium filament burning up in air or pure oxygen.
    • Senku tosses the grenade using an atlatl or spear thrower.
    • The flash grenade is made of a flash bulb and a 15-volt manganese battery of the same style made for the phone. A spacer attached to a long string keeps the circuit open until the grenade reaches the right altitude where the spacer gets pulled out. The circuit is completed and the bulb ignites.
  • The glass used to make the blacklight is called Wood's glass. It acts as a filter that lets ultraviolet and infrared light pass while blocking most visible light. It was formulated in 1903 but its use in blacklights is being phased out.
    • Incandescent blacklights were the earliest type of blacklight but they are incredibly inefficient since the tungsten filament produces little ultraviolet light. Thus, their output is limited and they get extremely hot from all the absorbed visible light in the envelope.


  1. Dr. Stone Manga: Chapter 63, Page 7

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