As he lowered himself over the wall and his boots connected with the ramp, Stevens came at him.

Vince saw the knife in his right hand, but there was no way of avoiding it without losing his balance on the narrow walkway. The tip of the blade caught in the wet mesh of his jacket sleeve as Stevens's body came into contact with his. He could feel the edge of the knife twisting and pushing harder into his arm. But he was above Stevens on the ramp, still standing on a dry section of the white-painted concrete, and was able to gain more leverage.

Shoving down with all his might, he shifted his attacker back, and in doing so freed Stevens's arm to slash at him again. This time the blade cut wide above his face, missing by several inches. Seizing the time created by the continuing momentum of the action, he brought his knee up to Stevens's groin, only to find the move blocked by the other man's leg. But the assault was enough to shift their balance. He could feel the ramp bouncing dangerously beneath them as they fell, rolling and sliding over each other around the sharp curve. Below, a number of penguins scattered madly into the water.

In the brief moment that Vince lost sight of the knife it came at him again, this time from above, arcing down and sticking into his left bicep. The jacket prevented it from penetrating deeply, but the sensation snatched his breath away and sent shockwaves through the nerves in his limbs. He rolled over the edge of the ramp and fell, narrowly missing another walkway. He landed in the shallow pool on his back, and the shock of the fish-reeking icy water threw him up on his knees just as Stevens dropped from above.

Vince brought his head down to protect himself. Stevens crashed across him and kicked down hard, catching him in the solar plexus with his boot. Winded, he slapped back into the water as Stevens rose and waded towards him, the knife gleaming dully in his gloved hand.

What made Vince grab the passing seabird by its feet and brandish it at his attacker he would never know, but the struggling penguin was understandably miffed at finding itself faced with what appeared to be a giant rival penguin, and started viciously slashing at Stevens with the sides of its razor-sharp beak. Within seconds it had sawn through the black leather collar of Stevens' tunic and was biting his neck. The assassin screamed, dropping the knife and falling back, but the penguin kept coming at him, nipping, snapping and chattering as it forced him under the ramp, where Vince was able to boot him hard enough in the side of the head to render him unconscious.

As he slipped and slid back up the incline, grabbing at the sides of the ramp to stop himself from falling, Vince snatched up the dripping envelope that had fallen to its centre. He looked back in time to see the penguin, satisfied that it had exacted vengeance on an interloper, hopping from Stevens's inert black and white body and swimming away with a satisfied wiggle in its tail. Without flight, thought Vince, but not without fight.

'OKAY, THERE'S a badge of some kind, red and blue enamel, with lettering on it. WBI.'

'The "Without Borders Initiative". What else?'

'Today's date, and some kind of serial number.'

'That's your pass,' said Masters. 'My guess is that he wants you inside the perimeter of the WBI's meeting-place. You have less chance of being arrested under suspicion if you're outside the immediate crime area. What else is there?'

'The final letter. I'll read it to you.'

The Challenge Of The Warrior Queen

'Fear not, isle of blowing woodland, isle of silvery parapets!

Tho' the Roman eagle shadow thee, tho' the gathering enemy narrow thee,

Thou shalt wax and he shall dwindle, thou shalt be the mighty one yet!

Thine the liberty, thine the glory, thine the deeds to be celebrated.'

Farewell, Queen Of The Iceni.

Your fate decided by a hare,

Loftily charioted, keeping victory in defeat,

Where you were slain, your subjects now depart.

'This looks like it might be easier than I expected,' said Vince, cradling the phone beneath his chin. 'I thought the last one would be a bastard. I've got one hour to solve it, which would bring us to eight o'clock.' He checked his watch, but it had been damaged in the fight. His arm throbbed dully, the bloody wound sticking to his shirt. 'It's Boadicea, isn't it? She fought in the shadow of the Roman eagle. She was the queen of the Iceni in Norfolk. Wasn't there something about a running hare?'

'That's right,' replied Masters, relaying information from Arthur Bryant. The Romans plundered her possessions, flogged her and raped her daughters, so she led an uprising against them. She needed to convince her troops by showing them an omen, so she released a hare which ran in an auspicious direction, one that revealed the favour of the goddess Adraste, the bestower of victory.'

'Hence keeping victory in defeat?'

'No, that probably refers to her name, which means "victory". It was the only thing she kept. The battle was lost and she was killed, but her fame lives on because, paradoxically, she came to represent the kind of patriotic fantasy figure that children were raised on, this image of the heroic champion who freed the Britons. I'm sure she figured heavily in Sebastian's upbringing.'

'The lines are from Tennyson,' Maggie called out, 'as is the reference to her being Loftily charioted. He helped to raise her profile immensely, and a statue was built to her.'

'Where?'

'It's on the Embankment right near Big Ben, absolutely enormous, you can't miss it. I guess that must be your final destination.'

'No,' said Vince, staring out into the rain. 'Where you were slain, your subjects now depart. He's playing another trick on me.'

'What do you mean?'

'Oh, come on. It's one of those stupid schoolkid things you remember from history class. He doesn't mean me to go to her statue on the Embankment at all. He wants me to go to King's Cross station. Boadicea is supposed to have fallen in battle there. Platform Ten, to be exact.'

'God, I'd forgotten all about that. The station's meant to be built on the ancient battle-site, isn't it?'

'The thing about her being buried under the platform is just a piece of nonsense,' he heard Bryant say, 'one of those things teachers always used to tell children to spark their interest.'

'But you're right, it fits,' Masters agreed. 'They can't be holding an international conference on a train, can they?'

'I imagine they're boarding a train for somewhere in the countryside,' Vince replied. 'If it's due to set off at 8:00 a.m., they'll be gathered in the station concourse beforehand. They might even be there already, which means that Sebastian can strike at any time.'

'Don't you see how dangerous it is, sending him there alone?' said Maggie. 'It's what Sebastian is expecting. At least let Arthur call someone. Suppose Vince gets inside the security area and a bomb goes off, or a sniper opens fire? Suppose he's injured? Or arrested, just as the League has planned? Vince has played into their hands every step of the way – and we're still helping him because that's the only thing we can do. But if we don't do something different and disturb their expectations, they'll have won. It may already be too late.'

The open line on the speaker-phone crackled between them. They were assembled around the dining-room table once more, but were unable to agree on a course of action. When Maggie complained about this, Masters snapped. 'Well, what do you expect?' he shouted, 'we're academics. We've never had to put anything into practice.'