Enthusiastically praised by Charles Lamb and A. C. Swinburne but unjustly neglected since the early twentieth century, Thierry and Theodoret dramatises events from medieval French history, and makes them particularly memorable by portraying the scariest villainess in early modern drama -- the unblinkingly evil Brunehaut, whose relentless pursuit of self-determination in the guise of unchecked sexual freedom leads her to plot the assassination of her two sons and a human sacrifice. The play explores the delicate nexus between misogyny, gender paradigms, and power in a patriarchal system, while glancing at recent political events in Paris and London in a way sufficiently aslant not to raise the censor's eyebrows. With its disenchanted depiction of royalty, its eerie instability in terms of genre, and its black comic overtones, Thierry and Theodoret strikes as a distinctive specimen of tragic drama in the Jacobean mould and ranks as one of the most powerful plays in the canon of John Fletcher and his collaborators. This Revels Plays volume is the first fully annotated critical edition of the play, and the first to attribute it to Nathan Field alongside Fletcher and Philip Massinger. It provides a thorough introduction reassessing the play's engagement with its classical and contemporary sources -- including Shakespeare -- and discusses the dating, authorship, and reception of this bizarrely captivating play, pointing the way for future scholarship. With its modernised spelling and detailed on-page commentary, this edition makes the play newly accessible to readers, students, and theatre practitioners.