A recovering alcoholic, teetering on the brink of relapse, uncovers a shadowy 12-step labyrinth of blackmail, human trafficking and murder while he probes the brutal death of his sponsor.

"An alcoholic near relapse probes the brutal death of his sponsor and uncovers a shadowy 12-step labyrinth of blackmail, human trafficking and murder."

Yes, there is indeed another shade of irony in his not being even close to sainthood! I agree with your tweeks and twists! Now, to build the layers of each personality like baking baklavah!
Thanks!

I realize that revisiting old habitats would would be triggers for old habits -- a serious enough threat to the character flaw.

But it seems to me it would make for a more interesting story (and more original?) if a good sponsor turns out to be a bad person. As you know, the AA program emphasizes that sponsor are no saints, and they are the 1st ones to say so themselves. Sobriety is a state of mind, not a state of moral rectitude. Even so, the undercurrents of psychological transference in the relationship make it almost unavoidable for newbies to look up to their sponsors as role models. And then to find out...

Anyway, it's your story. Good luck, whatever way you decide to tell it.