The Third Doctor > Jo Grant > Atlanteans > Kronos > Minotaur > U.N.I.T. > The Master > Medieval Knights
The Master summons a time pigeon and goes back to Atlantis where he finds a minotaur and other plot points.
The Second Doctor > Ben Jackson > Jamie McCrimmon > Polly Wright > Atlanteans > Fish People
The lost city of Atlantis, fish people, and a mad scientist who ISN’T The Doctor