Secret Islands is a hundred square metres of BDSM holiday flat hidden somewhere in the north of Essen, in Borbeck — around four kilometres from the A42 and seven from the Centro in Oberhausen. The address is not published: the venue withholds it for discretion and confirms it when you book.

The whole flat is yours for the length of your stay, with no reception and no one to meet. The key waits in a safe, and from the moment the door closes behind you the place is empty of everyone else. There is a living room with a St Andrew's cross and a rack, a large salon with a throne and a prison cell, bondage points in the ceiling, a quiet bedroom with a big bed and a massage table, a bathroom with both a shower and a tub, and a fully fitted kitchen. Up to six people, two double beds.

It is not a hotel and not a studio rented by the session — the venue is firm about that. It takes bookings for a few hours or for several nights, and it answers in English as readily as in German.