The TARDIS lands in the middle of the Trojan War, where the Doctor is mistaken for the god Zeus.

While Odysseus forces the Doctor to find a way to win the war, Steven decides to get himself taken prisoner in order to enter Troy and find Vicki and the TARDIS.

With Steven and Vicki being held prisoner by the Trojans, the Doctor's only hope of seeing them again is to suggest the idea of the Trojan Horse.

The TARDIS arrives in Tombstone, Arizona in 1891. Where the Doctor is looking for a dentist when he has a toothache, where The Doctor finds the local dentist is the famous Doc Holliday who is in a feud with The Clanton Brothers and their hired gunfighter Johnny Ringo, whilst local sheriff Wyatt Earp is trying to keep the peace. The Doctor, Steven and Dodo find themselves joining forces with The Clanton Brothers and Sheriff Wyatt Earp.

With the Clantons believing the Doctor to be Doc Holliday, Wyatt Earp takes him into protective custody but this leaves Steven and Dodo in danger.

Earp comes to Steven's rescue and arrests Phineas Clanton, prompting the Clantons to decide to enlist the help of Johnny Ringo.

The Clantons have shot Warren Earp, leading to a showdown between the two families with the Doctor powerless to prevent bloodshed.