Jonas Merrick. At MI5 they call him 'the eternal flame', because he never goes out. Never goes undercover, or on surveillance, or kicking down doors. If he's studying a map, he's probably planning his caravan holiday.

But what the hot-shots fail to notice in Jonas is a steely concentration, a ruthless ability to find the enemy who hides in plain sight like a submerged crocodile, waiting for prey.

Cameron Jilkes. A young man from a broken background, trained as a Jihadi in the harshest theatre of war. Coming ashore near Dover, he plans to live unnoticed, before unleashing a terrifying strike.

And this time, Jonas Merrick must go out - to hunt the crocodile himself.