She was about to put the key in the lock when she had a momentary flash of concern. What if this was a trap? What if Radecki or Krasic had forced Carol to make the call?

Petra pushed the thought away. Carol wouldn’t put another officer at risk like that. If she’d been coerced, she would have found a form of words that would have given Petra warning. She unlocked the door and stepped inside. The apartment was silent, though she could see the flicker of the TV screen from the hallway. She picked up the smells of sex and blood and froze where she stood. ‘Carol?’ she called out.

Nothing. Petra slipped her hand into her bag, where her standard-issue Walther PPK nestled in an easily accessible inside pocket. Cautiously, she drew the gun and slipped off the safety. Gently placing her bag on the floor, she held the gun in a two-handed grip as she inched forward towards the living-room doorway, her back to the wall.

She turned swiftly into the room, straight into a firing stance. What confronted her was far, far worse than she could have imagined. Carol lay in a crumpled heap, wrists and ankles bound behind her back with leather belts. Her face was a streaked mess of blood, saliva, mucus and tears. Her nose was swollen and angled improbably. Her eyes were invisible in the puffy purpling of bruised flesh. Smudged trails of blood and shit were visible on her thighs. There was no room for doubt about what had happened here.

‘Jesus Christ,’ Petra moaned. She crossed the room in rapid strides, sticking her gun in her waistband. Tears of anger and grief swelled inside her as she sought frantically for a pulse in Carol’s neck. Relief hit her as her fingers felt the slow beat of blood in the carotid artery.

What to do first? Petra hurried through to the kitchen and yanked out the drawers, looking for a sharp knife. She grabbed a dishtowel and ran it under the cold tap.

Gingerly she cut the belts away from Carol’s hands and feet, swearing as she took in the deep welts they left. Carol’s arms fell to her sides and a groan escaped from her lips. Petra sat down behind her and manoeuvred her into a more comfortable position, tenderly cradling her. She wiped the damp towel across Carol’s forehead, constantly repeating, ‘It’s Petra, Carol. I’m here for you.’

Within a minute, Carol’s swollen eyelids flickered, a thin gap appearing between them. ‘Petra?’ she whispered.

‘I’m here, Carol. You’re safe now.’

Carol struggled in her arms. ‘Tony. They’ve got Tony,’ she cried.

‘Radecki?’ Petra asked, no doubt in her mind who was responsible for this nightmare.

‘He’s got Tony. He’s going to kill him. He told me. He knows who I am. I’m blown. And he’s going to kill Tony because we killed Katerina.’