As Armand and Blodklutt turn around to face the crocodile, which has regained its senses, I move up behind Francesca and stare down into the bottom of the pit. It is bristled with foot-long stakes.

‘We’re trapped!’ I say despairingly. ‘We can’t get across that!’

Francesca licks her lips and studies the pit, her eyes darting over its every feature. ‘It’s too wide to leap over,’ she says under her breath. ‘And there’s no means of securing a length of rope to swing over. Which means we need to go across the wall.’

‘Whatever you are going to do, you had better do it fast!’ Armand calls over his shoulder. ‘We don’t have long.’

‘Across the wall?’ I say incredulously, noting that the corridor’s walls are made of smooth sandstone. ‘But there are no handholds. We’ll fall to our deaths!’

‘No we won’t. Watch.’ Francesca moves several yards back up the corridor, giving herself enough room to gain some speed. She then races forward and, just as she reaches the edge of the ten-yard-wide pit, leaps off to the right. Carried forward by her momentum, she races – horizontally – along the corridor wall and, pushing off at the last moment, lands safely on the other side of the pit.

‘Now I need you to do exactly the same,’ she says, producing a length of rope from her pack and throwing one end across to me. ‘But hold the rope as you run across. If you lose your momentum, I’ll be able to pull you over.’

Inspired by Francesca’s effort, I pick up the rope, take several steps back, draw a deep breath and race forward, my heart pounding. Pushing off with my left foot just as I reach the edge of the pit, I leap into the air and, assisted by the rope, race along the wall, the pit opening ominously beneath me. A second or two later, I arrive safely beside Francesca.

‘I can’t believe I just did that!’ I say in disbelief.

But the triumphant smile vanishes from my lips when I notice that Francesca is looking back across the pit, her eyes wide in alarm, locked on the crocodile as it launches itself at Armand and Captain Blodklutt.

Separated from my companions, I watch helplessly as the great beast directs its attack at Armand’s head. Ducking at the last moment, and avoiding the crocodile’s closing jaws by only a hand’s-breadth, Armand’s response is lightning-fast and lethal. His blades snake out, slicing through the soft flesh on the underside of the beast’s neck, splattering gore across the sandstone walls.

Its quarry having evaded its attack, and having felt the bite of tempered steel, the crocodile is driven into a rage. Thrashing its head about violently, it lumbers forward. But in the narrow confines of the corridor, Armand and Blodklutt hold the advantage, and their blades strike out in perfect unison. Only this time, they fail to find the soft underbelly of the crocodile, and their blades glance ineffectively off the beast’s scaled hide.

As Dietrich and Diego make their way across the pit, running horizontally across the corridor wall, I see the crocodile coil back. The next instant, with a tremendous flick of its tail, the beast propels itself forward, rearing onto its hind legs, lifting itself almost seven feet off the ground, and its jaws strike out at Blodklutt, who dexterously ducks beneath the attack, sending the crocodile’s head smashing – hard – into the wall. Before the beast has time to recover, the Captain drives his rapier up through the underside of its lower jaw, pushing with all of his might until the blade punches through the flesh and scales and three hand-spans of steel emerge inside the beast’s jaws.

The crocodile recoils in pain, but before it has a chance to withdraw from the fight, von Konigsmarck races forward to Blodklutt’s side and, reaching into the crocodile’s gaping jaws, discharges his remaining pistol deep into its gullet. Writhing in agony, the beast jerks its head back violently, pulling free from the Captain’s blade with a sick, squelching sound. With the smoke from von Konigsmarck’s pistol wafting from its bloodied maw, the creature then withdraws back up the corridor and disappears into the entry chamber.

There’s an expectant moment as the three swordsmen – breathing heavily, their weapons held at the ready – wait in the corridor, anticipating the beast’s return. But it doesn’t, and after a minute or so they sheathe their blades and make their way across the pit.