This is a complete ready-to-play adventure for Mage: The Awakening which can be dropped in to whatever else is going on in your chronicle with little difficulty, or used as a one-off. It uses the Storytelling Adventure System, which basically means that it's best run from the PDF as you get the advantage of extensive hyperlinking and the like.
The adventure really only works if your cabal has an established Sanctum and Hallow, because the plot involves having to fight to defend it: if you want to weave this into an ongoing chronicle, make sure that they have reached this point first. It all begins when someone comes round invoking the Right of Hospitality - the bounden duty to aid a fellow mage in difficulties by letting them stay for a while - on the grounds that they are being attacked by whoever the cabal's current rivals might happen to be. From then on, things go downhill really fast.
A lot of background material is provided about the people involved and what they are trying to accomplish, which enables you to play them to good effect. The plot's deliciously devious as well, and is laid out clearly once you've been introduced to the NPCs. There are opportunites for combat and for investigation and at least one point when your mages ought to be wondering what just hit them!