The prison constitutes one of the fields of research which, immediately and by general agreement, seem to be covered by the notion of “minefield”, in particular because the context has already been defined as a “social problem” and because the definition of a research project is not always easy. But there are other mines, traps, and theoretical as well as methodological questions not initially apparent which are not different from those existing in virtually all other fields. That is the type of mine we are dealing with here. The article describes a return to the original site after ten years and examines the problems which have beset a more recent research project. The profound changes which have marked the penal institutions for women in Portugal are presented and the discussion of the theoretical state of prisons and their borders on the outside worlds is re-opened.