The steady work of rethinking the fourth-century doctrinal controversies continues in this excellent monograph on one of the more enigmatic figures of the age. Sara Parvis, in her penultimate sentence, nicely alludes to Athanasius' famous smile and silence on the subject of his former ally, and it is easy to think that Marcellan theology is as elusive as any Cheshire Cat. But in this book Marcellus is treated carefully and seriously, not as a marginal eccentric but as someone representing a coherent tradition of theological teaching, a quite sophisticated Trinitarian monism along with a distinctive eschatology, rooted in earlier Asian and Antiochene thought (including even echoes of Irenaeus). The degree to which he and Athanasius were really at one on some of the sharpest questions of the period is a matter for fuller discussion. The Alexandrian's willingness, late in his career, to make room for some of the pluralist language Marcellus most fiercely opposed, must have taxed their alliance. And Parvis plausibly suggests that Marcellus' own silence in his last years was a deliberate tactical sacrifice to give some space to Athanasius and his colleagues to secure a sustainably broad consensus in the eastern Church. Among the many valuable new interpretations in this book, perhaps the most significant is Parvis's clear demonstration that the textbook story of eastern bishops reluctantly voting for Nicaea and then reverting to their preferred traditional pluralism or even subordinationism once out of sight of Constantine's police is mistaken. She scrupulously examines the attendance lists of various post-Nicaea synods and establishes that there is remarkably little overlap between bishops attending and voting for Nicaea and those who supported a broadly ‘Eusebian’ position in the forties and fifties. This reflects some credit (in the earlier part of the period) on the party-organising skills of Eusebius of Nicomedia; Athanasius' fulminations on the plotting of Eusebius are not just paranoia or empty abuse. Robin Ward's recent fine thesis on Eusebius of Nicomedia (as yet unpublished) will be a very helpful contribution in filling out the picture. There are other incidental points of real help and merit, including a good discussion of the date of the synod of Serdica – a notorious crux, for which Parvis adopts the solution recently offered by Richard Burgess, based on a confusion of cycles in the indiction calendar. This is not quite watertight, but it is probably the best suggestion yet for resolving the obvious mistake in the Verona Codex. This is a welcome study, authoritative, sympathetic and acute, which will undoubtedly contribute enormously to the next generation of scholarship on the period. The ‘lost years’ have been most effectively retrieved and narrated in these pages.