Dimitri fell into step with Erin in the lobby of Thames House.
"You're stalking me." She kept looking straight ahead, but he could see the beginnings of a smile.
"It's not stalking if I know your habits." Plus he'd been checking the CCTV cameras.
"Perhaps I should change my habits." She held the door open for him, which gave him the opportunity to smile at her.
"Fancy a walk?" At her hesitation, he added, "Just a short one."
"All right." As they crossed the busy road and headed towards the river, she put her hands in her pockets. There was a chill in the air. "How is life in G Branch?"
"Good. But that's what I wanted to talk to you about."
She stopped, looking worried. He had gone to the effort of talking to her outside the building, which could only mean trouble.
He put a hand up. "I just wanted to tell you I'm going undercover tomorrow, so it would be better if you didn't contact me until it's over."
She relaxed a little. "How long?"
"Few days, maybe a week."
"You're going to seduce another woman, aren't you?" There was a twinkle in her eye.
He smiled. "Jealous?"
"You'd love that, wouldn't you?" She elbowed him in the arm as she carried on walking.
"I'll be thinking of you," he promised, at her shoulder.
"I heard you had a bad day." Dimitri held up a bottle of wine when Erin opened the door.
"You look like you did too." He grimaced a little and ducked her hand, before she could touch his still-tender black eye.
Once inside he headed to the kitchen, to pour them a glass each. When he brought them into the lounge, she was on the sofa, wrapped in a blanket. He passed her a glass and sat beside her, careful not to sit on the blanket. "How's the river?"
"Wet." She took a big sip of wine.
His expression turned worried when he noticed she was shivering, despite the warmth of her house. "You did get checked over before you left?"
She nodded. "Don't worry, I don't have hypothermia. I even had a tetanus jab. I just keep shivering." She put her drink on the coffee table and pulled the blanket closer around her.
He put his glass down beside it and put an arm round her. She rested her head against his shoulder and he rubbed her back.
"What happened to you?" she asked, after a moment.
"When CO19 came in, they guessed who I was."
"And your girlfriend hit you."
She looked up, then. "Really?"
He shrugged. "Apparently I was his type."
She grinned. "Did you sleep with him?"
He shook his head. "Not enough Viagra."
She laughed, burying her head against his shoulder. He was still smiling when she raised her head again. "I'm glad to hear it."
They moved closer, eyes on each other. However, before they could do anything there was a hammering at the door and shouting to go along with it.
They both pulled back. "Are you expecting anyone?" he asked.
She shook her head.
Their jobs had made them both cautious and when she went to the front door he hid round the corner.
Erin opened the door the fraction that the chain allowed. Whoever was on the other side pushed the door, but the chain held.
"Where's Mike?" a woman shouted. "I saw him come in here."
Dimitri stepped forward, into view. "Kelly. What are you doing here?" He kept his tone light, keeping in character and not allowing her to see his worry at her following him without him noticing.
"Looking out for my brother. I knew there was something fishy about you."
"Sam broke up with me." Which was true, although it had been after he'd found out 'Mike' worked for MI-5. Not surprisingly, he'd refused to give the whereabouts of his sister, who'd gone on the run as soon as the rest of G Branch had turned up.
Something - or someone - hit the door hard. The chain broke, Erin flew back and Dimitri caught her to stop her from falling. It was Kelly with, as it turned out, a baseball bat.
"We can talk about this." Dimitri backed up, letting go of Erin.
Kelly shook her head. "No, you are going to release Sam or I'll bash your girlfriend's head in."
They both played their parts: Dimitri allowing his feelings to show on his face and Erin suitably scared. As they reached the stairs, Erin took two steps up it. Dimitri stood half in front of her, so it looked like he was protecting her, without blocking her.
"I can't do that." Dimitri held his ground and waited until Kelly came closer. Then he reached out for the baseball bat, making the move clumsy so she'd have time to move away from him and towards Erin. Who kicked at Kelly's arm.
The baseball bat went flying. Dimitri didn't stop to check where it landed. He was too busy grabbing Kelly and getting her arms behind her back.
Erin was quick to pass him some plastic ties - he didn't ask where she kept those - and he bound Kelly's wrists. Not that it stopped her from wriggling and complaining.
Despite having his hands full, Dimitri didn't miss the glance Erin gave to the top of the stairs. "Go," he said to her. "I've got this."
Erin went. Dimitri took Kelly to the dining room, out of the way, and tied her to a chair. Then he called in, to have her picked up.
Erin didn't come back downstairs until Dimitri's colleagues arrived, ten minutes later. Once they'd left, she drained her wine glass.
"Kelly escaped when we arrested the rest of the crew," Dimitri explained, standing awkwardly in the entrance to the lounge, looking guilty. "We thought she'd gone on the run. I should have been more careful."
Erin nodded and put the glass down. Dimitri took a step towards her. "I told them I roped you in on this because she wouldn't recognise you." He inclined his head towards the door to indicate he meant his colleagues from G Branch who'd picked Kelly up. For people who kept secrets for a living they could be terrible gossips sometimes.
"You led her here," Erin said quietly, staring daggers at him.
"I'm sorry. Rosie was never in any danger. There was one of her and two of us."
She shook her head. "And what if she'd had an accomplice?"
He put his hands out. "I'm sorry," he repeated. "Have me demoted, if you like. Bring me back to Section D where you can keep an eye on me."
She turned her back on him. "Go."
He stayed for a few moments, to see if she would change her mind, but she said nothing. He went.
When he reached the roof of Thames House she was already up there, leaning out on the railing, gazing at the city. When she heard him arrive she glanced over and stood up straight.
"Rosie's my priority," she said, once he was standing in front of her.
He nodded and gazed at his feet. "I can't guarantee her safety."
She looked out at the buildings glowing in the sunset for a moment and then took a few steps closer to him. He met her gaze, her eyes watery with unshed tears. "Thank you for not lying to me." She kissed him on the cheek, then carried on past him, back into the building.