Well, that's not really that difficult, as my players will visit the "club" as well.
As the former Hellfire Club of Sir Dashwood was formed by some influential people it would be logical, that the new incarnation is composed of similar people. A poltican might turn to the characters for help, he might have heard about the adept's field of expertise. He tells them, that he is blackmailed, because he visited a monks abby (the Order of St.Francis) where he took part in an "how shall i put this? Wild Party..." . That alone would be enough to blackmail him, but said event took an unexpected turn into an occult heathen ceremony (that's were the adept comes into play). He is expected to join the order and to do some favours for the order. He does not exactly know where the abby is 8he was blindfolded), but was told that the girls who attended the event were invited at (put fitting place and time here). So the sisters could arrange to be invited to the next meeting.
Another option would be to let the adept discover hints about an old occult society called the "Hellfire Club". If she decides to investigate Wescombe Abby (maybe for mystical knowledge fiiting for an adept), she and her sister might discover, that the "Hellfire Club" isn't as dead as it is supposed to be.
I found the characters from X-men's Hellfire club to great inspirations for the new members (Shaw, Madelyne Pryor the goblin queen, Emma Frost...)
There is also a map of the westcombe catacombs (one of the Wiki-links does lead to it, if i remeber correctly)
The Gem of Amara...
Official sponsor, of my killing you.
) interested in the Club?
