Prologue is the first chapter of Slender: The Arrival.
- Lauren (playable)
- Kate (scream only)
- Carl Ross (voice only)
- Slender Man (briefly)
- Charlie Matheson Jr. (briefly)
Following the mysterious disappearance of her best friend Kate, a young woman named Lauren goes over to her house in search for answers. Upon arrival, she discovers that tree has blocked Kate's driveway. Equipped with only a camera, Lauren decides to continue the rest of the way on foot.
When first entering the house, Lauren finds strange drawings all over the walls. She continues into the kitchen, where she finds an answering machine message from another of Kate's friends, named CR. She also finds a flashlight. Trekking upstairs, Lauren finds out that Kate's room is strangely locked. She then finds the key and opens the door. As soon as she enters Kate's room, Lauren hears a scream coming from the woods. Frightened and curious, she heads into the backyard to investigate.
She encounters a few generators, which light up the area, and stumbles upon an old, burnt house. Lauren then finds a small, starving figure in a corner. Approaching it will cause her camera to flicker through disturbing images. She immediately leaves the house. She soon comes across the entrance to Oakside Park. Inside, she finds Kate's journal and "FIND ME LAUREN" written in bold white letters. Lauren then enters the park in search of Kate.
- Slender Man will occasionally spawn outside Kate's House, but it will never attack you as it vanishes if approached too close or stared too much.
- Slender Man will also appear several times on top of hills in the distance as you travel towards Oakside Park.