The courier brought the institute issue slips and a copy of Zhao Heng’s batch ledger to the records table. Gu laid them beside Yun Cang’s catalyst sketch. The ledger showed a grey fragment logged as inert trace material and a separate impurity listed as the cause of the poisoning.
The two materials had been stored in adjacent containers. Their codes were similar, but not the same. A later copy had shifted the column line and made it look as though the fragment belonged to the dose formula.
Qinghe checked the medicine recipe. The poisoning impurity appeared among the intended ingredients, but the grey fragment did not. It had entered the batch as an accidental contaminant during routine handling.
“The fragment wasn’t a planned addition,” she said. “The issue slips should tell us how it got into the cup.”
Bai’s message confirmed that the confiscation record matched the batch number. The fragment had been catalogued as inert after the research committee closed Yun’s project, then returned to general stores. A clerk had handled the trial medicine without knowing what the grey trace was.
The handwriting on the handling line was faint. The courier said the archive had found a duty roster but had not yet located a signature sample.
