Charlotte Harris is a twenty-three-year-old nonspeaking autistic woman who works as a cleaner in the local church. Zakaria Rush is the new Director of Children's Ministries at the church. Zakaria gives Charlotte guitar lessons, and the two start to fall in love.
The Key to Charlotte contains examples of:
- As the Good Book Says...: Charlotte cites Philippians 4:13, "I can do everything through Him who gives me strength," while arguing with her parents about why they shouldn't worry about her relationship with Zakaria.
- Character Tics: Charlotte rocks back and forth to relieve stress.
- First Kiss: Charlotte has hers with Zakaria after she speaks for the first time.
- Hands-On Approach: Zakaria likes giving Charlotte guitar lessons because it gives him an excuse to touch her hands.
- Hates Being Touched: Charlotte normally hates being touched, and resists the urge to wipe her hand after shaking it with Pastor Ed. To her surprise, she finds that she doesn't mind being touched by Zakaria.
- Meet the In-Laws: Charlotte introduces Zakaria to her parents, who like him at first, until they realize Charlotte is romantically interested in him. They assume he wants to take advantage of her, like every other boy who's ever shown interest in her.
- My Beloved Smother: Charlotte's parents try to discourage her relationship with Zakaria to protect her from being hurt. Charlotte is irritated by their overprotectiveness.
- Parental Marriage Veto: Zakaria used to be in love with a woman named Rachel, but their relationship was ended by her meddling father, who Rachel still listened to even though she was an adult.
- Sensory Overload: Charlotte becomes overwhelmed at church and looks around for a quiet place where she can collect herself before she has a meltdown. To her dismay, every room is occupied. Just before she loses control, Zakaria finds her and takes her to his quiet office so she can calm down.
- The Speechless: Charlotte can't manage to put sounds together to form words, so she communicates with a text-to-speech program on her phone. She also knows sign language, but hardly anyone else does, so she doesn't use it very often.
- Tears of Joy: Charlotte's parents cry when they see the video Zakaria took of her singing.