A bit different from other offerings in the Dungeon Crawl Classics line, this book provides six loosely-linked complete adventures to weave into an ongoing campaign. As the party rises in level they unravel more and more of a dastardly plot being hatched by an ancient mage and (hopefully) find a way to thwart it!
Each adventure is well-suited to challenge a party at the level for which it is written, and all provide information that links on to the next one, although it's recommended that you do not run them back-to-back, but intersperse other adventures. The idea is that the overarching plot is rumbling away in the background, and that the party occasionally interacts with it, beginning by meeting some of the mage's minions scavenging for a certain item in a place where they happen to be right on up to the final adventure when they actually confront the mage. Each adventure provides good reasons for completing it, and is well-resourced and ready to run in a session or two. Maps and room descriptions are up to the usual high standard. The first adventure involves a delve through a cramped underground druidic community, complete with places that the party will have to squeeze through (unless they are exceptionally skinny)... but there's something down there that the mage would dearly love to have.
Subsequent adventures involve a visit to the crypt of a long-dead paladin which appears to have been defiled, an attack on the party by a drow assassin which leads to a fine trap-based delve, the exploration of a mine which just happens to be building something that mage needs to further his plot, and a visit to his former tower before the party is ready to attack his current stronghold and put paid to his evil plots. It all hangs together quite well - it's nice to have delves with a purpose beyond trying to find items to steal!
Overall, this is recommended if you want a bit of a story arc without having every detail of every adventure you run woven into it. Spread these out with other adventures in between and you'll give your party a sense of purpose without getting too far away from the series' approach of going into dungeons just because they are there.