It was mid-morning and they had been walking, then driving around Kings Cross for at least an hour, but there wasn't very much to see. In the aftermath of the murder the streets had emptied out, the winter daylight sending the girls scurrying home. The alley where Elizabeth's body had been found was cordoned off.

"S'gotta be a local guy."

Dempsey was back to chewing gum, she noticed. He'd taken over the driving now, and Harry looked out of the window at desolate north London.

"He's comfortable around here. And the girls are comfortable with him. Anyone unusual, not a typical punter, and they'd be suspicious. Working girls are savvy."

"Not savvy enough to avoid getting murdered," said Harry. "It is interesting though, that none of them have noticed anything. He blends in."

There had been hardly any leads to-date. The police were getting desperate; everyone hoped the intervention of SI-10 would help crack the case.

"That's what I'm tellin' ya. Guy's a regular. He knows how to put the girls at ease. You gotta talk to them a certain way, and they know you know the score."

"You sound like you know quite a lot about it Dempsey," she raised an eyebrow. "Much experience of hookers, have you?"

He scowled. "What's that supposed to mean? Jeez, can't I express an opinion without you making some snide comment?"

The angry bear was back. Harry sighed.

"Control to Charlie five" Chas's voice came over the intercom. She picked it up.

"Charlie five to control, over."

"Harry, we have a Tina Allen waiting for you to interview. She worked with Liz Jackson and saw her get in a car a couple of hours before she was found. "

"We're on our way, Chas." She turned to Dempsey.

"We need to get back to Base. Witness to interview. You want to be heading in the opposite direction."

He sucked in his breath irritably. "Makepeace, it's a one-way system. I can't just turn around!"

"I know that. If you turn down one of these side streets, we can take a short cut back to the junction though."

"Can you not tell me how to drive? You're always doing this, just because you've lived here longer. I can find my way around just as well as you, sweetheart."

"I'm not telling you how to drive; merely giving you a quicker way to go," he was making her hackles rise. "And don't call me sweetheart."

Even as she heard herself speak, she knew how she sounded: ice-cold and haughty. All the things he'd thought about her when they first met.

"Oh whatever" he almost shouted, and she gripped the dashboard as he swerved the car violently around a bend.

After a few minutes' silence she tried to ease the tension.

"Can we not fight please? It's almost Christmas. Whatever happened to peace on earth, goodwill to all men?"

He glanced at her. When he spoke, his voice was calmer.

"Don't think the suitor's heard of them things, even if he does like to send Christmas cards. Anyways," he coughed, "I ain't thought about Christmas. It's not like I've got anything special to do. Just another day to me."

His words stopped Harry in her tracks. How could she have not thought of it? Of course he didn't have anywhere to go for Christmas. He had no family in England. His friends were mainly SI10 colleagues, as far as she knew. She forced a laugh.

"Surely one of your adoring girlfriends has invited you round for turkey and mince pies?"

He snorted. "Adoring girlfriends? What are you talking about, Harry? Spend so much time doin' this job, I ain't got time for any of that."

Was it relief she felt at his words? If it was, it was quickly replaced by guilt. She didn't want to think of him alone at Christmas. Should she invite him to spend the day with her Father? It didn't have to mean anything, just a goodwill gesture to a partner away from home. I'll speak to Daddy this evening, she thought.

When they got back to the office, Tina Allen was waiting for them in an interview room. Her bleached blond hair was pulled back tightly from her face and the fug of smoke in the room indicated that the cigarette she was pulling on was by no means the first. She looked much older than her 27 years, but the streets did that to you, Harry knew. Her heavy black eye makeup was smudged from crying.

They sat down opposite her. Dempsey leaned forward, and Harry gave him a warning look. Be gentle, her eyes said.

She didn't have to worry.

"Hey Tina," he reached over and patted her hand briefly. Harry was touched by the softness in his voice. She remembered his angry outburst in the car. At times like that, it was easy to forget this other side to him. He's complex, she thought.

"I know it must be really hard on you, thinkin' about that's happened to Liz, but we need you remember whatever you can. Might help us catch the man who did it to her. Now you saw Liz get into a car?"

Tina looked up. She drew heavily on her cigarette, then nodded quickly.

"Yeah I saw 'im. The geezer. Not 'is face up close like, but his silhouette. And the car. It was sort of a maroon colour, y'know? Dark red?"

"That's good, Tina." Harry smiled at her encouragingly. "Do you know what make it was?"

"Naah, I'm rubbish with cars" she gave a weak smile. "About the last thing I worry about when 'am working. It was newish lookin', I suppose."

"What about the guy?" Dempsey studied her. "Try and remember, anything at all."

"Like I said, it was dark and I didn't see his face. It all 'appened so fast. One minute me an' Liz was stood at our regular spot, then he comes along and we hugged goodbye. I said I'd meet 'er at the corner in an hour. But she never come back."

Her eyes filled again. Harry looked at her urgently. "We want to catch him Tina," she said. "We need him to stop doing this. Is there anything – anything at all – that sticks out?"

Tina closed her eyes. "I think 'e was blond, as far as I could see," she said. "And not skinny. Not old, not young. That's all."

She stubbed out her cigarette, leaned back and sighed deeply.

"Can I go now? Me kid's at me Mum's. I gotta pick 'er up."

"Of course. Thank you Tina." Harry smiled. "I'm so sorry about Liz. We're going to get this man."

"You'd better." Dempsey escorted her out of the interview room. Harry stared at the still-smoldering cigarette butt in the over-flowing ashtray. She wished she felt as confident as she sounded.