Tacitus, a Roman senator of the early second century, wrote the Annals, a history of the emperors from Tiberius through Nero. This is Book 5, and only fragments survive. In the last book, Aelius Sejanus, commander of the Praetorian Guard — the emperor's household troops — had become a second ruler while Tiberius withdrew to Capri, off Italy, and governed by letter and suspicion.

Sejanus is still at his height. What should follow is his fall: a sudden letter from Capri, the tearing down of his statues, and the killing of his people. The pages break in that turn. Macro is already waiting to take over the Guard. Other writers, Dio and Suetonius, cover some of the missing hours. You walk into a torn climax of Tiberius's terror, not a quiet year.