In the first book she appeared, Sheena knew her brother overheard their uncle, Dr. Deep, who was talking about a search for a mermaid that was spotted in the bay. She followed Billy that night when he went searching for the mermaid himself, only to be separated from him by a large hammerhead shark. Before he could get away however, he was bitten in the leg by the shark. Thankfully, he was rescued by the mermaid before the shark could kill him. The mermaid was captured by her uncle and his assistant Alexander, brought to the boathouse the Deeps lived on and placed her in a tank. However, she and Billy protested against the mermaid's captivity. Billy, Sheena and the mermaid finally communicate with each other, after feeding her Alexander's marinated squids. That night, Alexander and two goons he hired tried to steal the mermaid, only to be delayed by Dr. Deep and his nephew and niece. Unfortunately, the Deeps were tossed into the tank, which got tossed into the bay, and the crooks took off on their own boat with the boat. Just when they thought that they would drown, the Deeps were rescued by a whole group of mermaids and mermen. Understandably angry at the humans for taking their friend, they forgave the Deeps after they explained what had happened. They also helped them stop Alexander and his goons and freed the captured mermaid. The next day, after Alexander and his henchmen were arrested, Dr. Deep was visited by the zoo executives again and was given money to fund the search for the mermaid. But Deep said no and told them that there are no merpeople, pleasing the children.
In Creep from the Deep, Sheena gets captured by Captain Ben and his crew of zombie pirates along with Billy. She and Billy then get an invitation to HorrorLand where they meet Matt Daniels, whom Sheena seems to have a crush on. Along with her brother and several other kids, Sheena is one of the Very Special Guests.
Sheena is eleven years old, tall and skinny with straight raven-black hair and dark blue eyes.
Sheena is a girl that has no imagination. She never used to think that there were any monsters in her closet when she was little and she likes real things and cold, hard facts and doesn't like games and is very skeptical. This makes her the opposite of her brother, who thinks she is no fun. She has a tendency to be sarcastic with him and always seems eager to hear about the terrible things that could have happened to him when he did something foolish or pay him back for his tricks. But even though they don't always get along, they still care for each other and she can be kind and thoughtful. And like Billy, Sheena is always interested in her uncle's work. She also proved to be a good student at school and she always shuts everything out to do her homework. Her catchphrase is "no such thing."
List of appearances
- Goosebumps HorrorLand
- Creep from the Deep
- Monster Blood for Breakfast! (not seen)
- The Scream of the Haunted Mask
- Dr. Maniac vs. Robby Schwartz (mentioned)
- Who's Your Mummy?
- My Friends Call Me Monster
- Say Cheese — and Die Screaming!!
- Welcome to Camp Slither
- Help! We Have Strange Powers! (does not speak)
- Escape from HorrorLand
- The Streets of Panic Park
- Goosebumps Graphix
- Terror Trips
- Goosebumps The Movie
- Monster Survival Guide (mentioned)