"We are taking social networking back from the bullies and paedophiles. We are also taking it back from scammers, trolls, and scammers."
The black hooded masked man speaks directly to the camera in an electronically altered voice. He sounds and looks straight out of a horror film.
His goal is not to scare you, unless of course you are an anonymous trolling or cyber bully. He could turn out to be your worst nightmare.
He gestures at an abusive comment made on a TikTok account by a woman in another video.
"What would you do if a stranger made this comment to your mother, sister, daughter, or wife?" We would say, "Stupid game, stupid prize."
This is the catchphrase for the Great Londini, an internet movement that gained two million followers in just months.
Online trolling is the game. The Great Londini will track you down.
You may believe that you can hide behind an anonymous username if you are a troll. Londini believes that he can uncover your true identity in seven to eight clicks.
If you are a child, your teacher will try to inform your parents or school that you are abusing other people online.
If you are an adult, or have made a sexually explicit comment on a video of a child, he will likely tell you. This could mean notifying your employer, or calling your local police department.
Moderation vigilantism is when users of a platform take it upon them to clean up the app.
It's something TikTok doesn't like. Nine accounts have been permanently deleted from the Great Londini, while the tenth account has been suspended multiple times.
There are many platform rules that Londini is accused of violating, including bullying and online harassment. Londini disputes all of these accusations.
He said in one video, "Until every bully racist or scammer is off the app, we are going nowhere."
"We are the anti-troll"
Who is the man behind this mask?
He is known as Leo. He is not his real name and he is often threatened with death. Leo sometimes takes off his mask in his TikTok Lives, but he still chats with his detractors and fans.
Leo is in fact the public face for a group of volunteers with mixed military and cyber security experience.
He spoke to me from an unidentified location in the US and said: "We are anti-troll." You're being trolled if you're on TikTok right now.
Isn't content moderation TikTok?
Leo states, "They are not doing it."
We do tell TikTok all. We give TikTok all information. The account is reported to us."
TikTok claims it takes great care to protect its users and has added new features such as allowing users to select who can comment on their videos and filtering out certain words.
"We know that there is no end to our efforts to protect our users. This is why we will continue investing in our products, teams and features to ensure TikTok remains a safe place for our users," a spokesperson stated.
When it comes to content moderation, the platform has a huge task ahead of them. TikTok claims that they removed 61 million videos within the first quarter 2021. 91% of these videos were taken down by TikTok before any user reported them.
The origins of tragedy
Londini's quest to defeat bullies was born from tragedy. The 14-year-old autistic boy of Leo's friend took his own life last year.
"My friend, after a while, when he was grieving said to us, You know, part of why he felt so depressed was because he was being harassed on social media.
Leo, along with several friends, tracked down the bullies who tormented his son at the father's request.
We were able give him the information and tell him to do what he needed. He reached out to his parents, and he received some closure.
The friends continued to work together. They decided to continue working on TikTok under the name of the Great Londini, a combination Houdini (the operating system) and Linux (the name).
Fans of The Great Londini are so passionate about their work, they tag the account with videos and comments every day in the hope that Leo and his team will catch another troll.
However, this fandom has a price. The movement could sometimes become the thing it hates.
Some supporters become bullies because they are so passionate about their cause that they break The Great Londini’s rules as well as TikTok’s Community Guidelines.
BBC speaks to TikTok user about online abuse she suffered after her videos on Memorial Day were criticized by the Great Londini.
Liz, a peace activist described the day when the US pays respect to military personnel as "an entire holiday dedicated to murder."
This provoked an angry response. Liz claims she was subject to a torrent of abuse from people with Londini usernames. They told Liz to kill herself and even contacted her former employer in an attempt to fire her.
Liz stated that it was hypocritical for them to be an anti-bullying account. However, many of their followers bully people on the platform.
Londini expels users from their network when they break the group’s rules. Leo, who was a US Marine and is quite sorry for Liz's fate, also expels them.
He says, "I understand their passions, especially when they are veterans." "But we try not to lead by example. "We don't harass her. I wish this woman all the best."