Achilleid is a fragmentary epic in Latin by Statius, who lived in the late first century AD. Only the first book and the first few hundred lines of the second survives, for about 1100 lines of poetry.
Statius apparently intended to tell the whole story of Achilles in the Trojan War, expanding beyond the events of the Iliad, and began in medias res, with the onset of war and Thetis's inability to prevent it. Desperate, she retrieves her son from Chiron, his centaur tutor, and takes him to the peaceful isle of Scyros, where she has him hide, in drag, in the women's quarters of king Lycomedes's palace, where he is passed off as the tallest and most unladylike of the king's daughters. While incognito, Achilles rapes and impregnates a very confused Deidamia, Lycomedes's eldest and most beautiful daughter, and she bears Achilles a son in secret. Only when Ulysses (Odysseus) and Diomedes are dispatched to find Achilles is the ruse exposed. Achilles makes an honest woman of poor Deidamia and they spend one lawful night together before he is hustled off to Troy. At the beginning of book two, Odysseus recaps the causes of the war and tries to make it personal for Achilles, and that's where Statius leaves off.
This translation by Stanley Lombardo is fast-paced and easy to read, and a good way to dig into the broader Trojan War mythos. Achilleid and another complete work by Statius, Thebaid, though almost unknown now, were popular during the Middle Ages--Statius even accompanies Dante for part of his climb up Mount Purgatory in The Divine Comedy.
The tedious introduction by classicist Peter Heslin is almost as long as the extant portion of Achilleid itself. Heslin essentially recaps the events the poem, blow by blow, with a lot of modern postmodern-ish interrogation of the text and Statius's intentions. Heslin thinks Statius is trying to undermine the authority of Homer's epic and call the seriousness of the Trojan War story into question, or something. He repeatedly refers to events in Statius's poem as having been "suppressed" by Homer, who lived at least eight- or nine-hundred years before Statius, on the early end of what is essentially an ancient fandom that was revised, retconned, and expanded upon long before those were vogueish internet activities. "As he narrates the events that have been whitewashed out of the epic canon," Heslin writes, "Statius demonstrates the mechanisms by which they came to be erased."
And so forth. Yawn.
This is absolutely worth checking out, but only for the text of the epic itself.