James Baron heads to his futuristic gentleman's social club, where explorers and rich men-about-town congregate to drink and socialize. Many are known for their exploits in space, and James is planning his own, crossing the sunny side of Mercury called the Brightside which no one has ever accomplished because the heat is just too intense as that side of the planet was always facing the sun. One man almost made it, a Peter Claney, but he was the sole survivor of the expedition and became a recluse once he got back to Earth. Peter corners James at the social club to tell him that he should drop the expedition, but James is insistent and wants to learn more about the process. Peter then tells James about his past and the experience trying to cross the Brightside.

Peter's story involved different members of various militaries and scientists, all telling them that trying to travel across the 770 Fahrenheit surface was a mistake. There were many minor troubles that plagued the planning for the expedition, but they ended up leaving on time. They were joined by a climber who had a problem with authority, and was their major problem. The climber, McIvers, wanted to travel miles ahead of the group and scout about, and was sullen when told to stick with the group. McIvers takes increasingly dangerous choices until the rest of the expedition can't stand him. McIvers eventually goes too far and sends himself over a ledge and everyone except Peter dies trying to save him. Peter spends the next week driving back across the landscape they had just traveled.

James blames McIvers, but Peter tells him that he's wrong. The Sun was beating them at their own game and would've killed them if they had stayed behind schedule the way Peter was making them by acting so cautious. As Peter leaves, he turns and asks James if he can join on the expedition.