A horrible substance

"Methyl Alcolyl" used to keep food cold in refrigeration is instantly addictive if ingested. A man uses this to get people hooked and force them to enslave each other. Two of my friends are dragged through a portal and spend years under him. Finally he lets one return home and none of us dares to hope that she'll escape; her friend stands up and attacks her when she gets to the airport. The friend is killed violently. After the girl gets home she talks casually about needing a source of the drug before she can decide where to move.