‘Will you stop it!’ Puddle roared.

Moll’s eyes sprang open. It was dark outside now.

‘Enough is enough!’ Puddle shouted again. ‘You’re going to get somebody killed!’

Moll tensed. The shouting was coming from higher up the lighthouse. She reached a hand down for her quiver, but remembered she’d left it outside the kitchen.

‘I will NOT have this, Dorothy!’ Puddle boomed.

Moll breathed a sigh of relief that it was the lighthouse playing up and nothing worse. She listened to the storm outside, still raging against the window and the darkness. Puddle had lit a candle while they were sleeping and its light flickered across the bed. Alfie stirred, then opened his eyes and looked at Moll.

‘I’m going up to speak to Puddle,’ she whispered. ‘Stay here with the others.’

Alfie nodded sleepily and Moll turned to Gryff. His eyes were open, staring blankly, and when Moll saw them she squeezed her fists hard. ‘Come on,’ she breathed, helping Gryff from the sofa and grabbing her coat. ‘We’ve got to work out why the bones sent us here.’

They climbed the cold stone steps up another level, past a room filled with spare lamps, until they reached the very last floor of the lighthouse: the lantern room. It was smaller than the rest, hexagonal in shape, and boxed in on every side by large sheets of latticed glass that were only just holding out against the rain. In the centre of the room there was a big, glowing lamp, surrounded by hundreds of pieces of beautiful, specially-cut glass, casting a beam of roving light out on to the sea – and, beside that, stood Puddle.

Moll watched from the doorway. ‘What’s Dorothy up to?’

Puddle jumped in surprise, then, on seeing Moll and Gryff, he smiled. ‘What isn’t she up to, more like . . .’ He rolled the sleeves of his cagoule up and placed a hand on a lever beneath the glass lens, then pushed. From the base there came a grinding sound, like a clockwork wheel turning. ‘The lamp needs winding up every two hours,’ Puddle muttered. ‘She’s high maintenance, I’ll tell you that.’ His muscles flexed and he kept pushing. ‘Her lens collects light from the lamp as it turns and directs the rays out to sea as a single beam. Clever old thing, isn’t she?’

Moll nodded. ‘Oak would’ve liked to have seen this.’

Puddle looked up. ‘Who’s Oak then?’

Moll was silent for a moment. ‘Someone who looks out for me, even when I’m annoying.’ She picked at her coat. ‘He got injured trying to protect me and I’m hoping this amulet might make things better.’

She padded towards a window with Gryff. The storm outside was furious. Huge waves battered against the rocks at the bottom of the cliffs, hurling themselves again and again amid the rain and wind, and thunderclaps ground out from the night sky, shaking the whole lighthouse.

But still Dorothy’s light shone out, scouring steady beams over the sea. And then her lamp began to flash on and off, not regularly as it had been doing before, but in a haphazard, stuttering way. Seconds later, it juddered to a complete stop, lighting up just one place.

‘Dorothy!’ Puddle hollered. ‘Stop messing around!’

But Moll was only half listening. She screwed up her eyes against the windowpane, ignoring the rain that lashed against it.

‘What’s that just round the coastline – where the beam’s shining?’ she asked.

Puddle followed Moll’s gaze. ‘That there’s Devil’s Drop where the river spills out into the sea.’

Moll nodded. The roar she’d heard when they arrived at the coast earlier suddenly made sense. Because pouring over the edge of the cliffs in a bay just round from the lighthouse, and only visible from this height, was an enormous waterfall. Torrents of water cascaded over the lip and plunged down into the sea, sending up metres of foaming spray. Moll watched as the water fell, great curtains of white crashing down into the sea. The lamp flashed on and off again, jerking light then shadow over the falls, but it refused to turn regularly as Puddle wanted it to.

‘No one ever goes near there,’ Puddle added. ‘A ship called the Craggan sank before the falls years and years ago. There are rumours that the dead sailors’ bodies haunt the wreck so people tend to steer clear.’

Moll carried on watching, mesmerised by the gushing water. The lamp flickered again and again over Devil’s Drop and Moll turned to Puddle. ‘The Oracle Bones sent us to the Blinking Eye. Maybe – maybe – the lighthouse is trying to show us something.’

Puddle snorted. ‘Dorothy? She’s just having one of her moods.’ He bent down to try and fix the lamp again and the rain beat harder against the windows, seeping in through unsealed cracks.

Moll frowned. ‘But the way the lamp flashes on and off – it’s not just random.’ She gasped. ‘Look, Puddle! There’s some sort of pattern!’

Puddle stood beside Moll, his eyes squinting into the darkness. ‘Is that . . .’ His voice trailed off into a whisper.

‘Is that what?’ Moll asked eagerly.

‘Long long long, short, long, short, short . . . You might be on to something after all . . . This looks like a code!’

Moll’s eyes grew large. ‘How do you know?’

Puddle watched intently as the lamp flicked on and off over the waterfall. ‘Because I recognise the patterns. I think it’s Morse code – an emergency code sent through signals.’

Moll’s breath misted up in a circle on the pane before her. She rubbed it away. ‘Do you know what it means?’

Puddle reached behind him and grabbed an old parchment map rolled up on a table. Unfurling it and turning it over, he drew a pencil from his cagoule pocket and began to write. ‘Dashes for the longer stretches of light, then we draw a diagonal line when there’s a pause with no light at all, then dots for when it flashes in short bursts.’ Before long, Puddle had scribbled a line of dashes and dots:

_ _ _ / . _ . . / . . / . . . _ /

‘What does it mean?’ Moll asked again.

‘Each set of dashes and dots between a diagonal line is a letter.’ Puddle ran his pencil over the symbols, then looked up at Moll. Her eyes were wide and green against the night. ‘I’ve got a word,’ he said.

Moll nodded, hardly daring to speak. Beside her, Gryff leant close.

‘OLIVE,’ Puddle said. ‘The code reads: OLIVE.’

Moll raised two hands to the glass and watched the waterfall crashing down over the cliffs.

‘Does that mean something to you?’ Puddle asked.

The longing inside Moll ached. ‘Olive was my ma. The Shadowmasks killed her.’

Puddle looked from the parchment to the waterfall, then back to Moll. ‘Well, I never . . .’

Moll nodded. ‘The amulet is my ma’s soul . . . and I think Dorothy’s trying to tell me that it’s trapped near Devil’s Drop.’

The rain beat against the lantern room and thunder growled across the sky.

‘There is a cave,’ Puddle said slowly, ‘behind Devil’s Drop. Only no one’s been in it since the Craggan sank.’

‘Because of the rumours of the haunted wreck?’ Moll asked.

Puddle nodded. ‘Them – and the swell is so strong round the falls that any sailor would be mad to steer their boat towards it.’

Moll dug her hands into her coat pockets. ‘That’s where the amulet is; I just know it. We have to go there.’

‘You’ll be killed out there on a night like this!’

Moll bit her lip. ‘I’ll be killed anyway if I stay.’

A whistle sounded sleepily from the doorway and Scrap appeared, dreadlocks wild about her face, her striped flag knotted under her chin.

Moll looked at her. ‘I think we know where the amulet is, Scrap.’

Puddle fiddled nervously with the zip on his cagoule. ‘It’s too dangerous. You’re just a kid, it’s the middle of the night and we don’t even have a boat to—’

His words were cut short by three loud raps coming from further down the lighthouse. Knocks on the front door echoed through the building.

Moll glanced at Puddle. ‘Are you expecting someone?’ she said slowly.

Puddle frowned. ‘No.’

The knocks sounded again, louder this time.

Alfie and Siddy appeared in the doorway behind Scrap. The storm and Puddle’s shouting earlier hadn’t bothered them too much, but knocks in the night – that meant trouble.

‘We shouldn’t answer it,’ Alfie warned. ‘It could be them – the Shadowmasks.’

The knocks didn’t come again. Just the rain beat at the lighthouse, clawing at the windows with slippery fingers. The lamp flashed on and off, still repeating the pattern of Olive’s name. But a feeling was growing inside Moll, whispering to her quietly. Whatever had been trying to get inside the lighthouse hadn’t gone away.