The question was answered when he saw a dark, sinuous shape speeding underneath the water. It was directly ahead of the bireme. The serpent was heading straight for them.

‘Dead ahead!’ Dion cried. ‘It’s under the surface!’

He nocked an arrow but the serpent was too deep. As the silver silhouette passed out of sight beneath the ship, deep enough to avoid the ram, he only saw that the creature was fat, and longer than the ship by half a length. White-faced sailors peered down, hanging over the rail as they wondered where it would next appear.

Making a guess, Dion raced along the open deck to the ship’s stern. He stood on his toes as he leaned against the rail.

Fifty feet behind the vessel and slightly to port, a scaled triangular head shot to the surface. Dion immediately drew the bowstring to his cheek and sighted along the shaft, aiming for the soft skin between its jaw and the frill behind its neck. Releasing the arrow, he grabbed another from his quiver and loosed again.

The first arrow tore into the silver flesh just behind the frill but didn’t sink deep. The second bounced off its skull.

More arrows filled the air a moment later as half a dozen archers fired together. The serpent plunged back into the water, thrashing its huge paddled tail in agitation.

‘Turn us around!’ Roxana roared.

Executing the turn at practice was one thing, but to be traveling so fast and then have half the oarsmen back while the other half continued to push forward made the vessel groan like a wounded beast. The Anoraxis heeled to the side and anything loose rolled across the deck.

The mast creaked alarmingly and Dion ran to the ropes holding the top of the sail to the upper beam. He knew the risk of the ship turning so hard while on sail: if he didn’t act quickly the mast could snap. He unhitched one line after another, careful of his hands as the whistling rope shot away once it was unfastened.

‘Get that sail down!’

Sailors ran to take over and with most of the work done he left them to it, earning a quick grateful nod from the stocky captain. He now ran to the bow as the chase began in earnest.

‘Ramming speed!’ Roxana cried.

With the turn complete, the drum increased to a beat so fast that Dion wondered how any oarsman could keep up with it. He heard a whip crack below and winced: a slave had just lost part of his skin.

‘Where is it? Come on, men. Talk to me!’ Roxana bellowed.

‘Dead ahead, cap’n!’ a sailor shouted.

The oars tossed the sea into white foam, leaving surging swirls in their wake. The marine infantry hefted their spears. Archers waited with arrows nocked.

The serpent shot out of the water ahead, nearly leaping in its haste, flying forward as its head again submerged.