From publisher blurb:
"This tower is quite tall, reaching over 500 feet in height. It’s also old, at least a few centuries, though others claim it was built a thousand years earlier. Whenever it was erected, it’s clear that its construction took a long time. Comprised of countless pale gray bricks, most of the tower is unremarkable save for a few features.
It has no visible door nor windows, and though faded paintings at the base might have helped solve the puzzle of its origins, graffiti and weathering has long obscured any such clues. Today, the answer to that mystery depends on the person asked. Claims have been made that its construction was ordered by wizards for some mysterious arcane experiments, while others suggest purposes of a more divine or sinister nature."
The purpose of these books is to help DMs put together an interesting encounter in a short time. Each Adventure Keys release does this by starting with a unique location that can be inserted seamlessly into an existing world with little or no modification. They are modular, with many options and variants available so that the DM can customize it to suit their needs.
There are six sections that include the Location, Hooks & Goals, Characters, Trappings, Threats, and Changes. All but the first have multiple options each, and since the DM isn’t limited to using only one option, the variations available are quite numerous. Sections can be used or ignored at the DM’s discretion, or even modified based on the situation or to scale its Challenge Rating.
The options are deliberately non-specific for ease of use. The DM can include them as they are, combine them, or use them for inspiration to create an entirely new options.