Anxiously, she checked her watch. Less than half an hour before they set sail. When she returned to her cabin, she would try out the tools she had purchased on the bolts on the balcony railing. Later tonight, when they were travelling at top speed and the rest of the passengers were sleeping, she would get to work on unscrewing the rail. Then it would be goodbye, Mark, and by the time anyone realised he was missing from duty, it would be too late to find his body.

‘Is decaf okay?’ Paula held up a coffee pod.

Anna nodded as she pulled her pink beret off her head. ‘Decaf’s good. Where’s Tommy?’ she asked. ‘Still in the bar?’

She saw the look of suspicion that Paula shot her, and smiled. ‘Isn’t that where they all go when they get day release?’ she laughed.

Paula laughed with her, but to Anna it sounded forced. She put the mugs underneath the fancy coffee maker in turn. When they were filled, and the aroma filtered through the room, she gestured to them before heading to the bathroom. ‘Back in a sec,’ she said, closing the door gently behind her.

Anna sprang into action. From her pocket she withdrew a small vial of crushed zolpidem and divided it between the two mugs, giving them a shake to mix the dark powder with the granules. Then she moved to Paula’s bag on the counter and peered into it, careful not to disturb the objects inside. Spotting what she was seeking, she pulled out Paula’s iPhone and pressed the home button. A text from Tommy flashed up on the screen, a short message asking where Paula had gone, telling her he had bumped into the lads and was having a drink in the restaurant. She should come straight down to dinner when she was ready and meet him at their normal table.

She let the screen fade to black before returning to her chair and slipping the phone into her own bag just as Paula emerged from the toilet.

‘How are you feeling now, after your nasty fall on deck?’ she asked.

The kettle clicked off, and Paula silently filled the mugs.

‘Milk?’ she asked. ‘Sugar?’

‘No, thanks,’ replied Anna, accepting the cup Paula passed her.

Paula sat down heavily in the other chair. ‘You called it a fall,’ she said bluntly.

Anna creased her brow in faux concern. ‘Yes, I saw Tommy this morning at breakfast and asked how you were. He said you’d had a nasty fall, were really shaken up.’ She paused. ‘I was here last night. You were very upset. Did you hurt yourself?’

Paula’s face drained of colour. ‘Tommy said I fell?’ she asked, her voice suddenly hoarse.

Anna frowned. ‘Yes, Dermot said the same.’ She leaned forward, looked Paula in the eye. ‘Why do you ask?’