I just picked this up. Scenarios are a number of dungeon crawls for the solo/coop Rangers game.
https://www.drivethrurpg.com/product/374317/Rangers-of-Shadow-Deep-Dungeons-Dark
The quest that began in Across the Wastes continues in Dungeons Dark!
This new mission includes 4 scenarios that use a classic dungeon-style set-up. The rangers must explore the labyrinthine corridors and rooms of the dungeon, fighting monsters, dodging traps, and perhaps even finding a bit of treasure, in their bid to escape the dungeon and continue with their quest. The book also includes an extra scenario, should the rangers get captured, and a section on ‘shadow magic’, which the heroes can employ at their peril.