Madeleine McCann's parents are marking her 8th birthday Thursday with a new book and renewed vows that their missing daughter will not be forgotten. 

In the book, simply called Madeleine, Kate McCann describes the moment she entered the British family's rental apartment in Praia de Luz, Portugal, at 10 p.m. on May 3, 2007, and realized Madeleine's bed was empty. 

Seeing the windows open, Kate writes that she felt "nausea, terror, disbelief, fear. Icy fear," and said to herself: "Dear God, no! Please, no!" 

On the Find Madeleine website, Kate says she has been consumed all this year with the book. It's being published Thursday, "which poignantly and coincidentally happens to be Madeleine's 8th birthday," she writes. "We hope and pray that it will bring us the result we long for and that not only the book but this whole ordeal and heartache will be behind us before too much longer." 

All proceeds from the book will benefit Madeleine's Fund, which Gerry and Kate McCann use to finance their continuing investigation into the mystery. 

Last May, on the third anniversary of Madeleine's disappearance, Gerry prayed there wouldn't be a fourth. "The fourth one would be even harder, because then she will have spent longer away from us than with us," he said.

"There are days when I just feel like shouting, 'Where is she?' " added Kate. "Madeleine should be back in our family, where we know she'd be happy and loved."