A year later, a fourth expedition lands, and it is successful. The crew's physician, Hathaway, reports that almost all Martians have died of chicken pox, apparently acquired from one of the previous expeditions. Captain Wilder lets his men drink and dance, but this angers the archaeologist in the crew, Jeff Spender. When Biggs, another member of the crew, becomes very drunk and goes to throw empty bottles in a nearby Martian canal, Spender hits him in the mouth. Spender feels humbled by the great Martian civilization and wants the rest of the crew to act dignified. The crew sobers up and goes to explore the town. Spender recites a Byron poem, "So we'll go no more a-roving," in honor of the departed Martians. He deserts the crew and begins to explore the Martian ruins.
Eventually, he returns, claiming to be a Martian. He tries to recruit Cheroke, appealing to the similarities between Martians and Cherokees, but Cheroke refuses. After killing five of the crew members, Spender feels ill and heads for the hills. Wilder finds him and tries to reason with him; Spender wants to kill all of the crew to stop humans from settling Mars. He wants to preserve and study Martian civilization. He refuses to back down, and so Wilder has to shoot him. This weighs on Wilder's conscience, and he resolves to continue Spender's mission and try to protect Mars. For example, Wilder sees Sam Parkhill using Martian ruins for target practice, so he knocks his teeth out.
This story is crucial to the novel. Wilder, Hathaway, and Sam Parkhill will all appear later, and Spender's ideas are very important. Spender's words neatly express many of the ideas that seem to have motivated Bradbury to write The Martian Chronicles. Through the rest of the novel, we will see that Spender's worst nightmare comes true. He was correct in predicting that corporate and government interest would dominate. Makeshift industrial towns go up everywhere, and Martian ruins are ignored.
Wilder's conscience wavers when he shoots Spender. In many ways, we can think of Wilder as standing for Bradbury. Bradbury and Wilder do not condone Spender's extremism, his murdering members of the crew. Yet they are convinced by his cause.
In the previous chapters, we have seen hints at how complex Martian society must have been, and this gives us reason to sympathize with Spender. It was wise of Bradbury not to explain explicitly how Martian society worked. Because we are only given hints, we want to unlock its secrets as much as Spender.
It is curious that Bradbury uses two Byron poems. Such literary references, however, exist throughout the novel, and sometimes they are more arbitrary than meaningful.