Solo and Kuryakin are told to escort a captured Thrush official, Egon Stryker, to Washington. Meantime, Waverly transports a man the agents are told is a double for Stryker. A Thrush team keeps trying to whisk Stryker away.
Solo and Kuryakin plan to blow up a Thrush treasury containing $55 million. The facility's cover is a casino. The agents recruit a young Minneapolis woman and coerce an expert safe-cracker as part of their plan.
An UNCLE agent transporting a Thrush device is killed when members of a revived Thugee cult in India rob a plane and cause it to crash. Solo picks up the trail of the murdered agent. He must deal with both Thrush and the cult.
The mysterious Hemingway causes havoc at UNCLE headquarters in New York through various means, including tampering with the facility's water supply and electrical system. This occurs on the eve of an important conference where UNCLE will host leaders from around the world. Meanwhile, Thrush's Dr. Egret and Riley, a Thrush mole inside UNCLE, conspire to assassinate the leaders. Solo and Kuryakin try to figure out Hemingway's motives. Virtually the entire episode takes place at UNCLE headquarters.
Solo is on a personal mission to help Col. Morgan, who was Solo's commanding officer during the Korean War. Kuryakin accompanies Solo. The agents become involved in a conspiracy where all is not what it appears.
A relative of Waverly's is being threatened if he doesn't sell shares in a company at a fraction of their value. Kuryakin is assigned to the affair, where his knowledge of gypsies proves useful. Solo, recuperating from a knee injury, provides limited assistance.
A pair of cousins has robbed a diamond syndicate of a huge amount of diamonds. They are blackmailing the syndicate; if they're not paid, they'll flood the international market, devaluing diamonds everywhere. Both UNCLE and Thrush are seeking to find the diamonds.
Thrush poisons Waverly, with plans to subject him to a procedure that affects the brain. The criminal organization has already experimented on others, turning a shipping magnate and a diplomat into failures.
An UNCLE translator, Mandy Stevenson, seeks excitement. Solo, feeling sorry for her, "recruits" Mandy to be a courier. In reality, she is only supposed to get Waverly more pipe tobacco. Things go askew when Mandy is given actual valuable information (a list of Thrush agents in France). UNCLE and Thrush comb New York to find Mandy.
UNCLE, seeking to infiltrate a meeting of terrorists, reluctantly recruits former agent Albert Sully, a supposed expert on one of the attending terrorists. In reality, he knows no more than UNCLE does and, in turns, seeks the help of a woman from his past.
A mysterious U.S. industrialist, Mr. Alexander, steals a new type of nerve gas from the U.S. Army. He leaves behind a small tablet with the number eight on it. Solo and Kuryakin investigate, with the help of Alexander's ex-wife Tracey, who seeks Alexander to sign her final divorce papers. The trio finds Alexander's parents working like slaves at a Greece rock quarry with the number five painted all around. After freeing the parents (and avoiding Alexander's thugs), they travel to a temple where they are captured by Alexander. It turns out Alexander plans to take over ...
Solo, Kuryakin and Tracey escape Alexander's death trap. The scene shifts to Washington and Virginia. Alexander breaks commandment No. 7 by seducing a prince's wife. He is planning on breaking No. 6 (Thou Shall Not Kill) and when that is done, his plot will be complete. Solo is menaced by a muscular thug while Kuryakin is endangered by employees of Alexander's farm in Virginia.
Thrush is developing an "ultimate computer," which, if it becomes fully operational, will mean the criminal organization even more formidable. The device is housed in a Thrush facility that uses a South American prison as a front. Kuryakin infiltrates it as a prisoner while Solo pretends to be the husband of an international prison inspector, Salty Oliver.
Thrush, at a base in the Middle East, is developing a "vaporizer," which dissolves almost any object. Kuryakin tries to enlist the assistance of a tribe of Arabs to help. Solo, meanwhile, convinces a soon-to-be retired Thrushman that he'll live longer if he switches sides.
Mr. Robspierre, a descendant of the original Robspierre, plans to launch a nuclear missile and destroy France's vineyards. By doing so, he hopes to restore the virtue of France. Solo works to protect the daughter of a scientist Robspierre abducted while Kuryakin infiltrates Robspierre's operation.
Solo and Kuryakin, aboard the Adriatic Express from Vienna to Venice, are seeking a Thrush chemical that can end the reproductive process in life forms. We meet Madame Nemirovitch, who claims to be the founder of Thrush.
El Supremo, the corrupt ruler of a Caribbean nation, abducts an opposition leader who had been under the protection of U.N.C.L.E. Solo and Kuryakin travel to El Supremo's country to free the opposition leader and bring down El Supremo.