This book examines the ‘rhetorical opportunities’ (p. 148) during which late antique bishops of Rome from Leo the Great (440–61) to Gregory the Great (590–604) made claims about the primacy of their ecclesiastical authority by evoking their succession from St Peter. In contrast to institutional histories of the papacy, which often follow a teleology of the inevitable ascent of the bishops of Rome as leaders of the Church, Demacopoulos argues that ‘the escalations of papal rhetoric, almost always linked to a Petrine claim, were often born in moments of papal anxiety or weakness’ (p. 2). Chapter i shows that ancient Christian stories about Peter did not emphasise his connection with the Roman episcopate until the fourth century, when Bishop Damascus tethered his authority to the cult of Peter's relics. It was not until the fifth century that bishops like Leo the Great (ch. ii) and Gelasius (ch. iii) asserted Petrine claims, but then only in specific diplomatic circumstances marked by uncertainty, when they anticipated that their authority would be ignored or repudiated by other bishops. Further chapters follow this line of inquiry through the early sixth century (ch. iv) and up to the papacy of Gregory the Great (ch. v). Here again we find bishops of Rome making claims about their succession from Peter almost exclusively in those situations when their authority is most precarious. Moreover, ‘despite many assertions to the contrary’, these pontiffs ‘rarely enjoyed in practice the authority [that they] claimed to possess’ (p. 103). In other words, papal power in this period was presumptive rather than actual. This thought-provoking work of revisionist history ends a bit too soon, however. Demacopoulos implies several times that the triumphant narrative of the rise of the papacy was a Carolingian invention (pp. 8, 40, 73), but there is an unspoken presumption that Carolingian texts and rhetorical strategies actualised the authority of the bishops of Rome in new ways. I am not so sure. This book raises a challenging question about when exactly the presumptive power of the papacy became by consensus real power. A final chapter that considered this question in the longue durée would have been most welcome.