Your child will read comics all day but shuts the book the second the page looks like all words. This is the climb across that gap. Start at the top, where a picture still carries every page, and each book after it hands your child a little more story to read and a little less to look at, until a page that's mostly text feels like nothing to worry about. Take the rungs in order. Every one was chosen to be barely bigger than the last.
What changes from the first book to the last is one thing: how much your child has to READ versus look at. The Bad Guys is nearly a comic, big panels and a joke a page. By the last rung the drawings have thinned to the odd doodle in the margin and the story is carried by the words, and your child got there without ever hitting a wall, because each step added only a little. Let every book feel easy before the next one. There's no prize for skipping ahead, and the whole trick of this trail is that it never once feels like a jump.