Plot summary
"If I may," Ambassador Kelefy put in diplomatically. "I agree with Mr. Bragan and Mr. Ferris. Americans do not fight even for millions with clubs." I could have named him an American who had used a blackjack on a fellow citizen to relieve him of $2.38, but of course he wasn't an oil tycoon.
— Archie Goodwin, commenting on an ambassador's naïveté, in "Immune to Murder", chapter 4
Nero Wolfe and Archie Goodwin travel to a hunting lodge in the Adirondacks owned by oil tycoon O.V. Bragan. They have been invited at the request of Theodore Kelefy, ambassador to the United States from a foreign country with large oil reserves, so that Wolfe can cook a dish of freshly-caught trout for a meeting of dignitaries at the lodge. [lower-alpha 1] In addition to Wolfe, Archie, Bragan, and Kelefy, five others are present – Kelefy's wife Adria; his advisor Spiros Papps; Assistant Secretary of State David M. Leeson and his wife Sally; and James Arthur Ferris, head of a rival oil company who is vying with Bragan for drilling rights in Kelefy's country.
At the first night's dinner, Bragan spites Ferris by arranging for him to sit uncomfortably close to the lodge's blazing fireplace. The next morning, Bragan, Ferris, Kelefy, Papps, and Leeson set out to fish on different stretches of the river that runs through the property, in order to catch trout for lunch. After Wolfe starts to cook, Archie goes fishing on his own and finds Leeson's body, showing signs of a fatal head injury. Once lunch is finished and Wolfe begins to pack for the return trip to New York, Archie tells him of the discovery.
The state and county police detain everyone at the lodge and soon establish that Leeson was murdered, most likely with a piece of firewood. District Attorney Jasper Colvin questions the group and begins to concentrate on Wolfe and Archie, hinting that someone may have hired them to kill Leeson. Colvin questions Wolfe about the fact that he cooked none of the trout Kelefy brought in, but Wolfe refuses to answer out of irritation over Colvin's attitude.
In a private meeting, Wolfe turns down Bragan's offer to hire him to catch the murderer. They are interrupted by Ferris, who threatens to tell the state attorney general of Bragan's attempt to influence Kelefy and Papps so that the negotiations will turn in his favor. Later, Kelefy asks Wolfe what he plans to say to Colvin about the unused trout. Wolfe offers to state simply that he chose not to cook them out of caprice, and also promises to say nothing about the confrontation between Bragan and Ferris. Kelefy takes off an emerald ring and has Adria give it to Wolfe as a token of gratitude. After they leave, Wolfe and Archie examine the stone and find it to be flawed and of poor quality.
Wolfe then calls his lawyer, Nathaniel Parker, and the two converse in French to prevent anyone listening in from learning about their discussion. He then has everyone gather in the main hall and calls the Secretary of State to explain his theory of the crime. The real reason he did not cook any of Kelefy's trout was that they were not fresh; they had been caught earlier and kept in a pool of water near the river. Surmising that Kelefy had simply had an unlucky day of fishing, Wolfe said nothing to avoid embarrassing him. However, when Kelefy had Adria give him the ring, Wolfe realized that it was meant as a bribe to conceal the truth, and an insultingly cheap one at that. Wolfe deduced that Kelefy had caught a creel of trout earlier in the day to allow him time to get the firewood piece and take Leeson by surprise. From Parker, he has learned that Kelefy is protected from prosecution by diplomatic immunity, and that anyone who swears out or serves a warrant against him will be subject to a prison term.
When Wolfe starts to comment on Kelefy's choice to have Adria give him the ring, she knocks the phone away and Sally angrily confronts her. Adria had seduced Leeson while he was stationed in Kelefy's country, and Sally found out and had him recalled to the United States. When Adria encountered Leeson again at the lodge, she began to seduce him again, prompting Kelefy to kill him.
Kelefy, Adria, and Papps leave the lodge to return home, Wolfe gives the ring to Colvin, and he and Archie depart for New York. Kelefy is executed a month later – whether in response to the murder or the failed oil-rights negotiations, Archie never finds out.
