"Well, there goes that theory," Brother Joseph said. He had not had much hope. Unlike Brother Gregory he could easily see Klacel doing something foolish, like burning military lists, and he had tactfully refrained from pointing out to Mendel that an external saboteur could not have got past a locked door in the first place, and could not have re-locked it upon leaving.

"But it at least casts doubt on the case against Brother Matthew," Mendel insisted. "When the tribunal meets, our Abbot will be able to show that a suspicious person was watching the monastery that morning, and could possibly have had something to do with the fire." Even he, however, was deflated by the failure to match the pollen samples.

"Let's test the others," Lindenthal suggested, picking up the remaining mud samples and handing them to the monk. Very slowly Brother Gregory began to prepare them by suspending the organic material in a slurry of water, and separating out the mineral crystals. He transferred drops of the opaque upper layer of liquid to microscope slides and began his search.

Not surprisingly, every sample tested contained at least one or more kinds of pollen grains, all different and none of them matching the pollen from their sample; until the last. He had almost given up, but when he put the final sample under the microscope, Brother Gregory almost jumped, and nearly broke his microscope again.

"Here it is," he shouted, pointing at the sample. "Exactly the same pollen, and lots and lots of it. This must be where the mud on the boot came from, there can be no mistake."

Brother Joseph checked his results, and just to be sure they prepared a second and even a third sample. But there was no mistake, the pollen samples matched perfectly.

"Where was it from?" Brother Gregory asked, still marveling at the positive nature of their findings.

"North, on Uzov road, on the way to the military camp," Brother Joseph said, reading the information from their carefully written paper packages. "That road is lined with Beifuss bushes all the way up, I bet if we go and collect some of the pollen directly from those bushes it also will match. I think we have found the place where the saboteur picked up the mud on his boot."

"Unfortunately that is a well traveled road, especially since the army moved in," Mendel said, shaking his head. "Everyone from around here has walked up that road, and smelt those bushes, at some time over the last week. The mud sample could have been on the boots of almost anyone. I'm afraid it does not help us much."

"Ah, well," sighed Lindenthal, "at least we tried. Have you any other ideas?"