A new character appears in the game - the Runaway Kid, one of the prisoners who is trying to escape from the Maw.
The Runaway Kid has a dream that he is swimming in water but then gets dragged down deep below the water by a big arm. Waking up from a nightmare, the boy leaves the children's room, which served as a prison cell for children. Along the way, he meets a girl with a flashlight, who is also trying to escape from the Maw. Thanks to her, the Runaway Kid leaves the Prison and enters the Depths.
Suddenly, the girl mysteriously disappears (presumably, she was killed by Leeches or the Granny), leaving only her flashlight, which the Kid picks up and subsequently uses in order to go through the darkest corners of the Maw. Once in the flooded sewers, the Granny, a resident of the Depths, who drags her victims down to the bottom of the water where she resides, begins to swim behind the boy. In the end, she drives the Kid onto one of the wooden platforms. In self-defense, he throws a television into the water, killing the Granny with an electric shock.
When the Runaway Kid gets out of the sewer, he is immediately caught by the Janitor, who puts him in a cage and sends him to the Kitchen.
In the second chapter, the Runaway Kid manages to free himself from a package sent by hooks to the Kitchen, but then accidently falls, once again, into the lower reaches of the Maw, where the main furnace, which is responsible for the operation of the vessel, is located. In order to continue his journey, the Runaway Kid needed to collect all the Nomes that worked in the place and use them to light a fire in the "heart" of the Maw, activating the ascent to transport coal to the upper tier. At the end of the chapter, the boy passes through the shelter of the workers and falls onto the roof of the elevator, in which the Lady was in at that moment.
In the third chapter, the Runaway Kid passes into the Residence. Note that in order to leave this place, he needs to collect the statues, which are the keys to the exit. To do this, he had to go around the entire library, avoiding an Eye and Shadow Kids.
Opening the passage, the Runaway Kid accidentally notices the Lady, with horror, considering her reflection in the mirror. Unfortunately, she notices the Runaway Kid and, after a little chase sequence, turns him into a Nome.
Having lost his true appearance, the hero leaves for the Guest Area, wherein one of the rooms he finds a sausage lying on the floor. So we find out that the Runaway Kid was the same Nome to whom Six ate alive to satisfy her hunger.
In the scene after the credits, we are shown a television in which a silhouette of a thin man appears in a few seconds, teasing the release of the second game.
Players play as a boy nicknamed the Runaway Kid. As in the main game, the protagonist has the ability to walk, run, jump, push, grab, and throw, but unlike Six, the Runaway Kid can also swim, which he uses in the Depths chapter.
In the second chapter, The Hideaway, players have the opportunity to use the Nomes as their allies, as the Runaway Kid catches and hugs them. After that, he can push heavy objects with them, open doors, or catch other Nomes, in order to eventually recruit a large group and use it to heat the furnace of the Maw.
Unlike Six, the Runaway Kid uses a flashlight, the light of which can not only illuminate various places, but can also be used to solve puzzles or to destroy the Shadow Kids who appear in the final chapter of the DLC.
- The Runaway Kid - The main protagonist of the DLC, whose main goal is to escape the Maw, similar to Six.
- Nomes - Small, humanoid creatures working in the Maw who play a major role in The Hideaway.
- Leeches - Minor enemies only found in the first chapter.
- The Granny - The main antagonist of The Depths. A monster with the appearance of an elderly woman, and lives in the sewers of the Maw.
- The Janitor - The main antagonist of The Hideaway. He is a blind man with unnaturally long arms and he watches the children of the Maw.
- The Lady - The main antagonist of the The Residence. A tall woman in a white mask, and also serves as the overall antagonist of the main game.
- Shadow Kids - Porcelain mask-wearing shadow creatures that serve as assistants for her.
- Six - A minor character who appears twice in the first two chapters.
- Guests - Minor characters that appear in the Guest Area. They cannot harm the Runaway Kid.
- The flashlight girl - A girl who briefly appears in the beginning of The Depths chapter. She disappears and leaves behind her flashlight, which the Runaway Kid finds and uses.
- Captured children - Minor characters sometimes seen in the backgrounds.
Others lead the escape but the Kid drops down into the Depths of the Maw. Little does he know that this murky place is home to the Granny - abandoned to decay and rage she will let no-one go. He must struggle on if he wants to survive, leap from floating debris to avoid being pulled into the treacherous waters, and find a way to create a path through the depths.
The first chapter of the DLC where the Runaway Kid explores the floated depths of the Maw. A new enemy known as the Granny lives within the murky waters. This chapter introduces water mechanics, notably the ability to swim.
The Kid has escaped the frying pan and is now in the fires of the engine room, where one wrong step can lead to his doom. Only by understanding the Nomes does he have a chance of making head or tails of all the machinery barring his way out of the Maw. But why are there so many Nomes hiding here?
The second chapter of the DLC that takes place in the Hideaway. The Runaway Kid is in the engine rooms of the Maw where a lot of Nomes reside.
The final chapter will decide the fate of the Runaway Kid.
The third and final chapter of the DLC that takes place in the Residence, an unseen part of the Lady's Quarters where the Runaway Kid will end his journey in the Maw by confronting the Lady.
- The 3rd chapter, also known as The Residence was initially slated for January but was pushed back to the next month.
- Secrets of the Maw is the first DLC expansion to adds more chapters.