The bell rang twice from the western approach and once from the Keystone chamber within the same four seconds.
For the length of those four seconds, the instrument room held two pieces of information that did not yet make sense together.
Two corridor signals would have been the entity's escalation the garrison had been watching for since the third incursion, the dual-incursion scenario Darak's analysis had flagged as the logical next step.
A corridor signal and a chamber signal together was not that scenario. It was something the analysis had not specifically described, and Aliyah understood in the same four seconds that not having specifically described it did not mean it was unrelated.
