Breaching the Threshold

Ascent complete. Three aggregate tiers surmounted. At the summit of the concrete landing, the exterior door stood sealed against nocturnal drafts. A thick rubber sweep pressed flat against a ribbed aluminum threshold bar. I wedged my clawed fingers beneath the stiff polymer lip. Upward leverage applied. The dense rubber flexed with dull resistance, yielding a gap of thirty millimeters. I braced my left knee against the concrete, drove my right foot strut through the breach, and hauled my chassis over the raised metal ridge. The seal snapped down behind my heels with a muted thud. Interior perimeter regained. Base secured.