(MAJOR SPOILER AHEAD)
You need to not pay the don's lackey when he stopped you,sleep for one day then go back to the slums,bunch of people will stop you then bring you to Don's hideout,you can pay the Don's or you can just refuse,choose to refuse to pay,then choose to work with him as a grunts,he'll give you a task to retrieve Cassie,go to Cassie safehouse in Abandoned Town,then talk with her about The Don,sleep,then when tomorrow arrives you will see that Cassie is gone,go to Don's hideout,you will see Cassie in there,you can either accept the pays or just outright refuse(i think the choice didnt matter? i only choose refuse to get paid),either way you will be given a task to rescuing Cassie,talk to Fawn in her condo,then sleep,then talk to her again,go to Police Station then talk to Arlene,its optional but,talk to Sammy for Don's lackey scheledule,also talk to Lin Lin for help,pay her,then ask about Don's man scheledule,then ask her to knock one of the guards later,talk to hobo in the middle,then he will ask for 1000 credits,you can either pay him or not,sleep for one day,then you will see theres no hobo in there,check the gentlemen club,you will see the hobo,after some harsh beating you get half of your money you paid him for (that is if you paid him before),go back to hobo refugee,then distribute your remaining credits that you paid the hobo for,sleep for one day,then check the police station,Arlene and Fawn will met in Fawn condo,then you can execute the plan,after you break out Cassie,she will be in Abandoned Town again,then you can renovate her safehouse basement for the private dungeon