This article draws on data from a larger study: a multi-site ethnography of the networks established by people confined in female prisons in the cities of São Paulo and Barcelona. Focusing on ethnographic data from my fieldwork in Barcelona, I analyze the displacements created by transnational drug trade networks which involve sex work and marriage in Spain. Brazilian prisoners in Barcelona (accused of ‘crimes against public health’ – involvement in the sale and transportation of cocaine) create aid networks involving the ‘owners’ of apartment-based prostitution and trade relations with men who are also prisoners in Catalonian penitentiaries. These entanglements forged between the transnational drug trade, the sex trade, and aid networks, as seen in terms of detention and migration trajectories of the Brazilians imprisoned in Catalonia, allow us to analyze the links produced between (il)legal markets and networks that are constituted by exchanges of money, affection, sex, imprisonment, and migration.