I wait for a gap in the fire then fly down, planning to charge at the portal. My feet have barely landed when a huge snake-like shadow rears up, dozens of monstrous heads snapping and snarling within the twisting mass of darkness. I hurl a ball of black energy but the shadows keep coming, wrapping about my body and turning me around so I can’t tell up from down. I cry out and the ground shakes as another bolt of magic lands to my left. Thiten gestures from the air. She’s clearing a path for me like she did on the beach.

‘Ivy!’

I look over my shoulder and Tom’s head appears at the top of the ladder. Panting hard, he snatches a quick breath. ‘Please, you have to listen! You can’t go through the portal!’

An explosion sounds above and he ducks down, disappearing from sight. I run over to him and his face crumples with relief when he sees me. ‘Please, Ivy, you have to be careful. Merlin’s cast a spell over the portal. He’s enchanted his sceptre so he can enter it – but if any of you go through you’ll die.’

Another blast sounds above and I shout, ‘How do you know this?’

He rubs his forehead. ‘I keep getting snatches of what he’s thinking. There’s so much cruelty in him, it scares me.’

‘OK, I’ll tell the others, but you have to go back to the house. It’s not safe here.’

‘You think?’

My wings beat the air and he does a quick double take, his mouth dropping open.

‘Please, Tom, I don’t want you to get hurt.’

‘If I stay, maybe I can help.’

More explosions boom above us and I’m torn between fighting alongside my sisters and making sure Tom is safe. There’s another reason I want him to leave. What if Merlin can see into his mind too? What if he wanted Tom to come here? I gaze into Tom’s eyes and see only goodness. An overwhelming sense of certainty grips me and I nod, sure I can trust him.

‘OK – but stay down here, out of sight.’

He nods and retreats down the ladder. When I turn around, the witches are lined up along the walkway, throwing different-coloured streams of energy in an effort to hold back the shadows. It seems to be working, as Morgan has climbed onto the platform and has her hand on the optic.

‘Morgan, wait! Tom says we shouldn’t go through.’

She turns and narrows her eyes at me. ‘Why, exactly?’

‘Merlin has cast a spell over the portal and we’ll be killed if we enter it. He’s enchanted his sceptre so he can come through unharmed.’