also known as substantive editing
This is the most comprehensive kind of editing. If your book is fiction, I will look at the structure, plot, characters, pacing, dialogue, setting, tone, and other elements to identify problems and suggest solutions.
If your book is non-fiction, I will look at the structure, writing, and use of images. I can identify what's missing and help you with any necessary research. And, if you need an index, I can do that as well.
This process takes time and communication, but, ultimately, it will result in a great project.
I teach a course on editing fiction at Ryerson University, but I also have a lot of experience working with non-fiction projects and, as a former journalist, I enjoy this kind of editing immensely.