The third century is a very difficult period to cover in any one study, particularly a relatively short work of introduction. Over the years, the political, military, economic and demographic challenges faced by the Roman Empire from the reign of Commodus to the accession of Diocletian have been the subjects of books in their own right, and there is a danger that any introduction to long periods of time ends up being too superficial, mostly laying out the historical narrative, or too devoted to a selection of themes, missing out on other important topics and so not offering the reader a sufficient understanding of the period in question. A.'s book in The Edinburgh History of Ancient Rome series faces these challenges and provides an interesting introduction to what A. calls the ‘critical century’. In a mixture of narrative and thematic chapters, A. delivers a general overview of the political and military situation under rapidly changing emperors and a more thorough discussion of aspects of law and citizenship under Caracalla (Chapter 4), religion (Chapter 6) and government (Chapter 8).

In Chapter 1 A. notes four important transformations between 192 and 284 which contributed to the changes Rome and the Empire experienced: the many wars Roman emperors or their commanders fought on different fronts simultaneously; the inability amongst the political elite to agree on a working system of succession; Caracalla's extension of Roman civic rights to the provincial population; and changes in the religious landscape in terms of both new and already well-known cults. A. points out how the second century was not quite as politically harmonious as earlier scholars thought it to be, not least Gibbon, and reminds the reader that M. Aurelius, the first emperor to have a son ready for succession, broke the tradition of adopting a successor from among the senators. Another important aspect is the changes to the organisation of the army, notably the transfer of resources from the people to the soldiers through taxation, thus changing soldiery from a civic obligation to a career.

In Chapter 2 A. combines historical narrative from the accession of Pertinax to the death of Septimius Severus with a survey of the available evidence: Cassius Dio, Herodian and the Historia Augusta are introduced together with epigraphic sources. A. offers a helpful introduction on how to read honorific inscriptions and gives the thoughts of the ancient historians space to express themselves in a number of useful citations. The question of how to use the Historia Augusta is complicated, but some thoughts on its availability and deficiencies as a source could benefit particularly readers who are new to both the period and the text.

The legacy of Septimius Severus is treated in Chapter 3, where A. focuses on Caracalla's and later emperors' road to power and the wars fought against external enemies. One of the more thematic issues treated is the Antonine Constitution (212): A. addresses the extension of civic rights and offers interesting observations on its implications. By becoming Roman legally, the new members of the Roman community were placed under the same religious obligations as the rest of the Roman citizen body. They were religiously Roman. Yet this, A. maintains, did not mean that Caracalla made the provincials culturally Roman.

The focus on law and citizenship is maintained in Chapter 4, where A. addresses both the empire's legal pluralism and its dynamics, the spread of Roman laws and the process of conformity towards Roman norms and legislation, which again, A. points out, was closely related to the spread of Roman civic rights. In Chapter 5 A. deals with the period between Maximinus and Philip, and employs both Sassanian and traditional Roman sources. Focusing on Rome's war against Sapor, A. offers a clear account of the military, political and financial difficulties Rome and Roman authorities faced in regards to Gordian III's eastern campaign, the rapid turnover of emperors, not least in the year 238, and Rome's defeat to Sapor.

In Chapter 6, A. focuses on changes in the sociology of religion in the construction of religious identities, which may have been the effect of the Empire. A. here sets out to establish when it was possible for the ancients to speak of plural religions and to understand the various religions as different cultural formations. A. addresses the question of religious practice both in private and in public. He hereafter returns to the effect the empire had on religious matters, using Decius' attempt in 249 to compel all residents in the empire to sacrifice to the gods for the eternity of the empire, and to prove their compliance with the order. The readiness amongst Roman officials to seek compromises is shown from examples of Roman officials who tried to come to terms with the Christians who would only offer prayers to (the) God. A. points out that Christians could have their faith as long as they conducted themselves as proper Romans.

Chapter 7 treats the period from Decius to Gallienus and how Rome suffered from repeated attacks, such as the establishment of the Gallic empire, and Sapor's attack and defeat of Philip the Arab. In Chapter 8, A. returns to the question of government and governmental practice and the change in status or the loss of status and civic rights which various social groups, including rich, free and poor, experienced in the period. Among other aspects, A. considers how senators lost their privileged position and the exclusive right to become emperors, and how the free poor population lost its privilege in terms of punishment and torture and was now treated in the same way as slaves.

In the final chapter, A. addresses the reign of Aurelian – his attempt to re-conquer and reorganise the empire and his interest in the sun god Sol Invictus. A. argues Aurelian's coinage reform was not particularly effective; and that the reabsorption of Gaul into the empire contributed in the longer term to the restoration of the Empire's social and economic order.

A.'s introduction is a very useful book and a valuable read for undergraduates or graduate students. It offers a clear and comprehensive introduction to a complex period, when the Roman Empire underwent rapid and dramatic changes on political, social, economic and military levels. Frequent citations of ancient sources provide a first-hand introduction to the material on which the arguments rest; excellent maps provide geographical clarity. A. has written a helpful introduction to a crucial and critical period of the Roman Empire.