"The Cheydinhal Sanctuary is but one of many secret Dark Brotherhood safe havens spread across the Imperial Province."
You've completed your contracts. You rose through the ranks. Lucien entrusted you with his life. After a long and difficult struggle, you saved the Dark Brotherhood from total annihilation. All that remains of the once proud and powerful organization are you, Arquen, and some lowly random murderer the two of you found. After all this you're satisfied with visiting Bravil once a week to collect a pittance of cash? Is there nothing more to be done? The story just ends here, like a bad movie? Not anymore. The time has come to reclaim lost power, to retake lost sanctuaries. To renew the Dark Brotherhood.
This mod adds a short series of quests to the end of the saga of the Dark Brotherhood which takes place after your first visit to Bravil after becoming the Listener. I always felt that Bethesda cut things short at the end of the quest line. You're just supposed to continue on, as though nothing was wrong, after your entire organization was brought to its knees? What about all those sanctuaries out there the game makes a point of mentioning but you never see? This is my answer to that and at least brings things to a more sensible close by the time you are done.
You may install this at any point during the game, it is not necessary to wait for the end of the quest line. In fact, some of the involved characters will exist and be out in the game world prior to everything turning for the worst. You may not even realize who they are when you find them. Once you have made it to the end of the quest line, visit the Night Mother statue in Bravil (and returned to Arquen with the info) at least once. You will be approached by a courier after 7 days to start things off. Though be patient, he needs to find you somewhere public.