It was only when Jason took them all out for ice-creams the next day that he really thought about leaving his home for the second time. Ice-creams were a childhood weakness of his; he had vivid memories of being about ten and savouring every last drop of an immense chocolate heap piled high onto a complaining cone. Unless his memories didn't serve him well, ice-creams had definitely got smaller since then. But no less tasty.

He felt more at peace than he had for a long while then, sitting on the seafront, one hand at Ariadne's waist and one clutching his cornet; beside them Icarus and Pythagoras were sharing an ice-cream, and Hercules (well, of course) had a double cone all to himself. They were all so relaxed that it was as if the drama of the past few days had never happened.

But it had, it had all happened, and now they were going to reverse their fate and return to Atlantis. And he would have to leave Cornwall behind, with its cliffs and its little seaside villages, with its ice-creams from musical vans that were always out of tune, with his own house and Mac.

His heart was torn. He loved Atlantis. But he loved his own time. And he preferred neither.

'I don't suppose there's anything else you want to see before we go?' he asked after a long, reflective silence. There were so many things he wanted to see or do again that now occurred to him, sitting here amidst a cloud of memories of childhood days out. He remembered cream teas in Devon – admiring Exeter Cathedral – he remembered the first time he had been up to London, and looked out over the whole beautiful city from the top of the London Eye.

'I don't think so,' said Pythagoras falteringly, with a glance in Icarus's direction.

'We should go back,' added Ariadne, though she too was watching Jason, whose face stayed in the same place whilst his inner self drooped.

'I'll miss England,' he said quietly, so that only Ariadne heard him. She understood – not entirely but somewhat – and squeezed the hand that lay on her hip, knowing that the homesickness she felt for her kingdom was equalled in Jason for his own home.

He had to blink back tears as a particularly strong recollection came to him – of Mac buying him an ice-cream, a double one, even though he didn't have much money, because it was his birthday. He had eaten it on the beach and then played in the sea with Mac, the latter splashing him, lifting him when the big waves came, and smiling at him with that grizzled visage that would always be the first image to appear in his mind when he tried to recall the face of his father...

'Ship's got to go in for repairs,' Mac announced when he returned home, slinging his coat onto the hook and looking through to the lounge. He was surprised to see Pythagoras and Icarus there neatly folding their modern clothes and garbed in their old-fashioned clothing; Jason was with them, talking occasionally; he looked up when he saw Mac.

'Repairs?' he asked.

'The engine needs looking at. We might have to take her up to the yard at – what?' Mac asked as Icarus stared first at him, and then at Jason.

'How long will it take?' he asked, trying to make the question sound innocent.

'Depends what's wrong with her. Could be a few days; hopefully not more –' Mac sighed a little, and changed the subject. 'I've got pizza for tea. I hope your friends like it.' He was addressing Jason now; Jason nodded vaguely, and Mac left the room to prepare the dinner.

'A few days?' Icarus echoed in a quiet voice, his face falling.

'There isn't a proper yard down here,' Jason explained. 'The nearest is about twenty miles away. And the engine's quite delicate. And old. They might have to replace it.'

It was only once he had finished his speech that he realised that this was probably not what Icarus wanted to hear. The boy was getting more and more homesick as the days plodded by, and now their plans for setting off had been postponed by at least the same amount of time again. Hopefully he could trust Pythagoras to comfort him, because otherwise –

'Icarus? I have something to show –' Jason said casually as he walked into the living-room. There he saw Pythagoras but not Icarus; the former had his head buried in a book, and glanced up as Jason entered.

'I thought he was with Hercules,' he said.

'And Hercules thought he was with you,' said Jason. With a slightly exasperated sigh he turned on his heel and proclaimed: 'Icarus!' to the entire house.

The walls almost shook with the shout – he never liked yelling in the house; as a child he had thought it would make the whole place collapse – but there was no response.

Pythagoras seemed to start at the silence. 'Where is he?' he asked at length.

'He must be in the house.' Jason paused. 'Perhaps he's hiding.' He didn't want to say sulking.

'What is he's not?' Pythagoras, his face now contorted with a sudden worry, jumped up, his book falling to the floor with a crash. 'What is he's – he said last night – no –'

And Pythagoras ran out of the room with uncharacteristic speed, his tunic flying behind him. Concerned, Jason immediately took off after him, calling briefly to Ariadne and Hercules that he was going out briefly; and he followed Pythagoras outside and down the hill to the seafront.

The young mathematician stopped for breath at the sea wall, staring out over the harbour. When he realised that Jason had followed him he turned back towards him, his face pale.

'The ship that was on the end –' he stammered.

And Jason, who was still looking towards the sea, let out a gasp of horror and dismay. There, perhaps half a mile from the shore, was a little yacht – the Lobster – with its sails raised, following an unsteady but determined path towards the horizon, towards the spot where the Scapha had gone in search of the submarine.

'Jason, that's him.'

Pythagoras stared at the boat as if he couldn't quite believe it; then, in a split second, he made up his mind and ran down the front, heading for the steps leading down to the jetties where the boats were moored.

'Pythagoras, wait –'

'I can't wait! That's Icarus! He's going to –'

Neither of them wanted to finish the sentence. Jason put out his arm; his hand brushed against the blue of Pythagoras's tunic, but his friend slipped from his grasp and ran down the steps. Quickly Jason glanced behind him – why? he didn't quite know – and saw suddenly the familiar figures of Ariadne and Hercules, both jogging to him, their faces expressing the worry he felt: they had evidently guessed what was going on.

'Come on!' he shouted; Pythagoras was already padding down the jetty, heading for the boat that would have the easiest access to the open water. 'Icarus is in that boat there –' he pointed vaguely towards the horizon '– we need to be quick, come on, come on!'

And a minute later they were all in a small motor-boat – it belonged to one of Jason's friends; he hoped he wouldn't mind him borrowing it – and speeding towards the ever-disappearing dot that was Icarus on what seemed to them like nothing short of a suicide mission.