Kindergarten teacher Kyoko Okudera is invited by her friend Madoka Uchiyama to eat at a Chinese restaurant, where Kyoko's boyfriend, Naoto Sakurai, works part-time at. The chef, Mr. Wang, receives the cursed phone call from his daughter, Meifeng's phone, redirecting the curse to inflict on him. Meifeng later arrives with a new phone and exchanges her new phone number with Kyoko and Madoka, the latter receiving the cursed call right afterward. Naoto heads to the kitchen and discovers Mr. Wang dead with half his face burned off.
Detective Takako Nozoe heads to the crime scene, learning from Detective Motomiya about traces of coal found in Mr. Wang's body as well as the fact that Yumi Nakamura is still declared missing ever since she killed Hiroshi Yamashita a year before. She personally questions Naoto the next day and tells him about the cursed call, the victims it claimed over the previous year, and its origin: Mimiko Mizunuma. Meanwhile, Kyoko's video chat with Madoka is interrupted when the former sees a black-haired figure about to reach her through the phone. She heads to Madoka's residence but is too late to stop her from being mutilated in the shower. Shortly after Naoto and Takako arrive, Kyoko receives the cursed call.
To help solve the case, Motomiya orders autopsies on all cursed call victims, including Mimiko, all of whom show positive of having traces of coal dust. In the meantime, Kyoko, Naoto, and Takako visit Mimiko's grandmother, who speaks of Mimiko being the daughter of a lunatic, who was killed by her Taiwanese husband. While serving his term, he felt chased by a little girl and decided to move to his hometown, Taipei, after his release. Takako contacts her estranged husband, Yuting Chen, who lives in Taipei, and from him learns that similar deaths related to cursed calls also happen all over Taiwan. Takako flies to Taipei to personally visit Mimiko's grandfather, only to find him dead while holding a cellphone.
Kyoko and Naoto decide to follow and help Takako to resolve the curse and are informed about the information she found: that the curse originally started from an abandoned coal mining town. The only survivor of the town recounts that a girl called Li Li had the power to curse someone into their imminent death verbally. The town residents, growing angered, sewed her mouth shut and sealed her alive in the mines. Takako then receives a call from Yuting, who has received the cursed call.
Heading to the town, the trio split up. Takako receives a call from Motomiya, who says that Yumi Nakamura's body has been found before the call abruptly cuts off. She heads into an open mine, encounters Mimiko, and passes out. After having a dream where she stops her twin sister, who died after receiving the cursed call years ago, from answering the ringing payphone, she wakes up and races to Yuting's apartment. She arrives right when his time is exhausted, yet since nothing happens, she reaches a conclusion that her sister has saved them. Meanwhile, Naoto manages to free Kyoko from being trapped by Li Li. However, when he realizes that Li Li will never let Kyoko go, he sacrifices himself by answering Kyoko's phone call and taking her place.
Takako is informed that Motomiya had died the day before while going to see Yumi's body, raising her suspicions. At the same time, Kyoko becomes confused when the police reveal that two bodies were found in the mines. Takako heads to Yuting's apartment and finds him dead in the bathroom, which she learns is her own doing from a video recorder. Checking her cellphone, she finds that she also receives a cursed call dated 5:58 PM, yet the current time is 8:05 PM: she realizes that she had died in the mines under the hands of Mimiko, who used her image to kill Yuting. Spitting a red hard candy, she smiles and drops it as the death ringtone is heard.Mimura as Kyoko Okudera (奥寺 杏子, Okudera Kyōko)
Yū Yoshizawa as Naoto Sakurai (桜井 尚人, Sakurai Naoto)
Chisun as Madoka Uchiyama (内山 まどか, Uchiyama Madoka)
Asaka Seto as Takako Nozoe (野添 孝子, Nozoe Takako)
Peter Ho as Chen Yuting (陳 雨亭 (チェン・ユーティン, Chen Yūtin)
Shadow Liu as Wang Meifeng (王 美鳳 (ワン・メイフォン), Wan Meifon)
Hakobu Okubo as Wang Jianfeng (王 健峰 (ワン・ジェンフォン), Wan Jenfon)
Karen Oshima as Mimiko Mizunuma (水沼 美々子, Mizunuma Mimiko)
Nana Koizumi as Li Li (李 麗 (リー・リィー), Rī Ryī)
Toshie Kobayashi as Gao Shumei (高 淑梅 (ガオ・スウメイ), Gao Sūmei)
Mariko Tsutsui as Marie Mizunuma (水沼 マリエ, Mizunuma Marie)
Renji Ishibashi as Yusaku Motomiya (本宮 勇作, Motomiya Yūsaku)
Haruko Wanibuchi as Sachie Mizunuma (水沼 サチエ, Mizunuma Sachie)
Kou Shibasaki, Shinichi Tsutsumi, Kazue Fukiishi, Anna Nagata, Atsushi Ida, and Kana Ito additionally appear as Yumi Nakamura, Hiroshi Yamashita, Natsumi Konishi, Yoko Okazaki, Kenji Kawai, and Rina Tsuchiya, respectively, through archive footage from the first film.