Among all the situations scrutinised by the International Criminal Court (ICC), Guinea has received the least scholarly attention. This article fills that gap by analysing the ICC's preliminary examination of Guinea (2009–2022) and testing claims that it represents a success for the Court. Based on 25 interviews in Conakry, it examines the Office of the Prosecutor (OTP) and its diplomatic engagement with state authorities, showing that Guinea is a partial success story. However, this success extends beyond the textbook application of complementarity rules – it reflects lessons learned by the OTP following previous diplomatic missteps in Guinea and other contexts. The analysis underscores that ICC scrutiny is deeply shaped by political dynamics, with favourable domestic and international conditions playing a crucial role. This case study not only sheds light on ICC-state relations but also offers insights into how the Court can navigate political challenges to fulfil its mandate.