During 05.009M42 an insidious menace began to plague the outer reaches of the Zadoc subsector. Near Betor, following the discovery of a tyranid hive fleet near the system, the Ultramarines send a strike force to hunt down the aliens, or at least determine their strength. The force, consisting of little more than a company, did not find the hive fleet itself, but recieved a distress signal from one of Betor's dependent colonies in the neighbouring system. When they arrived the inhabitants had been killed, and their brains removed. Shortly after arriving the force was attacked by Tyranids.

The Ultramarines, used to fighting this particular Xenos, fought ferociously and cleansed the small colony of the alien scourge. Upon receiving the Marines' report Inquisitor Hathek diverted to Betor to analyse the latest samples. It was clear the strain was new, and not part of Hive fleet Triton, but Hathek found the threat level of Nemesis, of which these tyranids certainly were part, to be marked as "low" on Imperial documents to which he had access. When he inquired further he found the information redacted, sequestered, or unavailable. Hathek resolved to get to the bottom of the mystery.

The Inquisitor's investigation took a new turn when more of Nemesis classified aliens were reported to be attacking Ork possessions on the extreme rim of the Mabb Nebula. Generally the Orks had faired badly, but Hathek was unable to confirm the identity of these Tyranids. They could easily be a Triton remnant and not related to the new classification. By the end of 05.009M42 the Inquisitor lord was becoming frustrated at his lack of progress. All he could find in the Inquisition logs was a brief report into the hive fleet:

+++CLASSIFIED+++
+++SUBJECT: NEMESIS+++
+++DESCRIPTION: NEMESIS. SMALL TYRANID HIVE FLEET IN ALEPH SECTOR. GENETICALLY DIVERGENT FROM TRITON/MEGALODON/KRAKEN/LEVIATHAN+++
+++SIZE: EST. 4 BILLION UNITS/20 GUARD REGIMENT EQUIVALENT+++
+++THREAT LEVEL: LOW+++
+++ORIGIN: UNKNOWN+++
+++FURTHER INFORMATION: R+++