You start at the Traverse, board a bus, and fetch up in a brothel on the other side of town, where a teenaged Nigerian girl has been pressed into sexual service.

She was so looking forward to being in Edinburgh, too, gawping at the city on the journey with us. Based on a real case of human trafficking in Glasgow, Cora Bissett’s production, written by Stef Smith and supported by the Scottish Refugee Council, is a powerful shock to anyone’s system.

Sixteen of us sit in the reception area before going down  to the bedroom, then the bondage room, where we are implicated in scenes of horrendous depravity and degradation, young Mary’s (Mercy Ojelade) humiliation made all the worse by its “theatrical” presentation with lights and video back-up.

Chillingly frank and direct contributions, too, from Adura Onashile as Martha the Madame, viciously entrapped herself, and John Kazek as pimp, client and blind eye-turning policeman.