Hermocrates (/hɜːrˈmɒkrəˌtiːz/; Greek: Ἑρμοκράτης, romanized: Hermokrátēs) is a hypothetical dialogue, assumed to be the third part of Plato's late trilogy along with Timaeus and Critias.
The intention of Plato to write this third dialogue becomes evident among others, from the following passage of Critias: Socrates: Certainly, Critias, we will grant your request [to speak] and we will grant the same by anticipation to Hermocrates, as well as to you and Timaeus.
Since the Critias recounted the story of the ideal state in ancient Athens of nine thousand years ago – and why it was able to repel the invasion by the imperialist naval power Atlantis – by referring to prehistoric accounts via Solon and the Egyptians, it might have been Hermocrates' task to tell how the imperialist naval power, into which Athens of Plato's lifetime had turned, had suffered a bitter defeat in the Sicilian expedition against Syracuse and eventually in the Peloponnesian War against Sparta – since he was a Syracusan strategos during the time of the Sicilian expedition.
In the video game Indiana Jones and the Fate of Atlantis the Lost Dialogue of Plato is known as the Hermocrates.
Its contents, however, are about the location of Atlantis, entry to the city, and notes about its inhabitants and culture.