In Islam, what happens to the soul of a body that has been decapitated?

I am writing a book with a character who practices Islam. I want to be 100% respectful and as accurate as possible. From what I have read, and I could be totally wrong here, a soul will not be admitted into heaven if they the person had been decapitated. When a person is decapitated, what happens to there soul? Do they go to hell? Are they forced to wander? RESPECTFUL ANSWERS ONLY PLEASE