It was twenty-five years since Katherine Beckett had died. She had been killed by a sniper at the funeral of the New York Police Department 12th Precinct's Captain Roy Montgomery. They'd been unable to find the shooter.

Richard Castle opened the email from his publisher and glanced over it, with the kind of glazed attention that had become the norm for him over the past two and a half decades. They'd be publishing the next Nikki Heat book in the spring. This would be Nikki's 23rd outing.

Around book 12 the critics had begun to say that the character was getting tired, the series overly formulaic and not that interesting. The books were focussing too much time on the home life of Nikki and her writer crime-solving partner, now husband, Jameson Rook. The criticism had become much less vociferous and public by book 14, which Castle had quietly been glad of. It seemed the critics were less bothered and were content to leave him to publish books as he did. They didn't need to review the books, the hardcore Castle and Nikki Heat fans would always buy them. It had been Martha's work, though her son didn't know it, that the critics had ceased mauling him. She'd begged, bribed and blackmailed. Alexis knew. It was one of the few things she would never tell her father, Martha had made her swear to that.

Heat and Rook were in their late fifties now. Though they were both settling and slowing down a bit, they were still solving crimes. It helped to keep the romance alive. Their kids – which had been born in books 6, 7 and 8 – were growing up fast and there was now a grandchild on the way. The pair already had two grandkids though – in book 4 Jameson had discovered a long-lost daughter, in her late teens, who he and Nikki had helped take care of while she made the transition from teen into adult. The daughter, Molly, was married now with two kids, and had helped Jameson and Nikki on a couple of cases. Jameson was endlessly proud of her.

Martha had spoken to Castle's editor, agent and publisher too when it became apparent that Richard's work was not as exciting as it once was. They had agreed to keep publishing the Heat series for as long as they were written. Luckily for all parties involved, they had not yet reached the point where a new Nikki Heat was losing them money.

The new book focussed a little more on Jameson Rook than the previous ones had. A subplot featured his mother passing away, leaving him parentless with Nikki doing her best to support him through the difficult time. Martha had passed away herself ten months ago.

The loft was a lot quieter now. Alexis had asked whether Castle would want to move in with them but he had said no. She made sure that she went around to see him as often as possible, but she never felt like she visited enough. She felt guilty for it, but there was little more that she could do.

Castle rubbed his third finger on his left hand subconsciously. The ring there was beginning to hurt and bite. He glanced down at it. He should really get it cleaned, but he didn't want to take it off. He had taken to wearing a ring there, a golden band, around book 5, when Jameson and Nikki had got married. He opened another Word document on his laptop and started to write Nikki Heat book number 24.

He knew, deep down, though he didn't like to dwell on it, what people were saying. That he should write something different, that the new Nikki Heat books weren't very good, that he was living on glories long since passed. That he should be done with Nikki Heat and write something else.

But he couldn't be done with Nikki Heat. As long as she was alive, as long as the character was alive, he had to write about her, about her and Jameson. Their lives, their family. Their love. The only way he would be able to stop writing about her was if she was dead. He couldn't, he would never be able to bring himself to kill off Nikki. Whenever she was in a tight situation he always made sure she could get out, or that Jameson would be able to get there in time to save her. That was the important thing, Jameson always had to be able to get there to save her. He always had to be quick enough.

Richard Castle started tapping on his keyboard, typing the first words of Nikki Heat 24. His fingers didn't move as fast as they once did and he had to write in a larger font size, sitting closer to the screen with reading glasses on. It was harder to get out of his chair than it had been and a couple of years ago he'd had Alexis help him move most of his belongings down from the second floor of the loft, so that he wouldn't have to go up and down the stairs as often. He didn't go out as often as he did, but when he did he was always surprised at how young people looked compared to him, and he sometimes heard whisperings of how old he looked for his age. He was not the man he once was.

Castle continued typing the opening chapter of the new book. It started with Nikki being ambushed while on a job, but Jameson sensed something was wrong and got there in time to save her. That was important. He always had to be quick enough to save her.

It was twenty-five years since Katherine Beckett had died.