In Vienna’s Café Central with its fine Neo Gothic vaulted ceiling, the four adventurers sat in a row in front of their crêpes and coffees, each intently viewing the glowing screens of their iphones.

“A veritable barrage of posts,” murmured the Sage.

“He’s desperate to throw us off the scent,” declaimed the Antipodean.

“Having blown his cover,” added the Recluse. “But now it’s out in the open, that all this high-flown theological sophistication is merely a cover for the watered-down penicillin racket, what else are we to do? We might just as well do as he says, and get the next plane out.”

At that moment, something caught his eye. A cat, that had been curled up on a window sill in the sunlight behind a gauze curtain, suddenly sat up, stretched itself, and ran across the floor in front of the four to a side door, which was standing just ajar.

Momentarily, the Trappist caught sight of a familiar face in the gap between door and doorframe. Then a waiter with a tray piled high with coffee cups and Viennese pastries passed by, so that when he could see the door again, cat and face were gone.

The startling disclosure had the others on their feet in an instant with a snapping shut of iphones, immediately followed by a dash for the door. The room to which it gave access was some kind of cloakroom, with cubicles for the staff, who looked atonished at this unexpected invasion of their privacy.

On the far side of the room was another set of doors, which gave out onto a small courtyard, on the opposite side of which was an dark opening, which seemed to lead to some steps. They were just in time to see the cat disappearing into the alleyway, as if it were following something, or someone.

The four split into two pairs - the Antipodean and the Nestorian summoning the help of the city authorities by means of their iphones, the Sage and the Recluse plunging into the dark alleyway and throwing themselves down the steps into the void, as if into the very bowels of hell itself - the Viennese city sewerage system.