οἱ ἐκ τῆς συνωμοσίας
From LSJ
ταῦτα δηλώσω αὐτός τε νοσήσας καὶ αὐτὸς ἰδὼν ἄλλους πάσχοντας → I shall describe those symptoms, since I myself had the disease and witnessed as well what others were suffering
Dutch (Woordenboekgrieks.nl)
οἱ ἐν τῇ ξυνωμοσίᾳ = de samenzweerders Thuc. 6.27.3 = οἱ ἐκ τῆς συνωμοσίας Plut. Ant. 13.4.
