is mapping the Delta Triangle, an uninhabited sector of the galaxy where a number of ships have disappeared since ancient times. The sensors become unreliable as soon as they enter the Triangle and they detect a Klingon battlecruiser. Before they can hail it, the enemy ship opens fire. The Enterprise
returns fire and the Klingon ship instantly disappears. Spock confirms that the Klingons' shields deflected the phasers, and the disappearance doesn't match that of a cloaking device. He suggests that it disappeared for the same reason that other ships have disappeared.
Sulu brings a 360-degree scan and picks up two more Klingon ships closing in. As Commander Kuri hails the Enterprise
, Kirk tells Sulu to plot a course to the spot where the first Klingon ship disappeared. He also has Uhura transmit their conversation with Kuri and send it to Starfleet Command, three weeks away. Kuri blames Kirk for destroying the first ship, the Klothos
, and refuses to accept Kirk's explanation. Kirk then orders Sulu to head for the coordinates. The Klingons open fire but the Enterprise
deflector shields hold them off... temporarily. As the shields go out, the instruments go haywire and subspace radio channels go dead. The Enterprise
disappears as Kuri stares in space.
crew suffers from vertigo as the ship materializes among what appears to be a graveyard of starships from throughout history. Many of them are designated as ones listed as missing, and Kirk suggests that they're in some kind of alternate universe. Spock agrees and notes that the two time continuums touch erratically. They followed the "window" behind the Klothos
before it could close. They scan for the Klothos
while Spock determines that some of the starships are centuries old. Among them is the Bonaventure
, the first Federation ship with warp drive. Spock picks up life and energy readings from a cluster of ships head.
Aboard the Klothos
, hidden within the mass of ships, Commander Kor orders his men to fire on his command. It moves forward and the Enterprise
spots it. As the Klothos
fires, their weaponry freezes. A second later, the same thing happens to the Enterprise
. As Sulu reports that all instruments appear normal, Kirk is transported away.
Kor finds himself in a council chamber. Individuals from numerous alien races are seated around him. When Kor tries to draw his weapon, his hand is burned and the council leader, a Romulan named Xerius, tells him that weapons are unnecessary there. Kirk transports in a moment later and Xerius welcomes them to Elysia. An Orion, Devna, speaks as the interpreter of laws. She explains that 123 races compromise the population of Elysia, dating back over a thousand years. Many of them were enemies on the outside but have learned to live together because they have no choice. All acts of violence are forbidden and violations are dealt with severely. Devna explains that they occupy a pocket of time, and nullified their weapons using the psionic abilities of some of their members. Devna tells Kirk and Kor that they are responsible for the behavior of their crew. Any crewman who engages in violent will be punished with total immobilization of their ship for a century. When Kor points out that they would be dead after a century, Xerius explains that time passes at a different rate within the pocket race. All of them are hundreds of years old. He admits that all of them have wanted to leave at some time, but it is impossible to escape.
Back on the Enterprise
, Kirk tells Spock and Scotty that they're going to get out. Scotty warns that the dilithium crystals are deteriorating and they only have four days left. Kirk puts Spock to work trying to find a solution to the trap that they're in.
Aboard the Klothos
, Kor's science officer Kaz tells his captain the same thing.
Xerius and Devna have one of their psychics, Magen, read the thoughts of the two new arrivals. She informs them that they are trying to solve the riddle of the time trap and escape. Devna says that the newcomers must try so that they will fail and accept their fate.
Spock eventually announces that there is no chance of a solution, just as Kor has his crew accelerate the Klothos
to escape. When Kirk wonders how he can do it, Spock says that the Klingons' engines, the equivalent of their warp drive, is deteriorating as well. The Klothos
strikes the barrier and is thrown back. Kirk, watching, wishes that they had succeeded. Spock says that their attempt has given him an idea. Later, he comes up with a formula that will let them escape. Scotty realizes that it means combining their ship with the Klothos
, and Kirk warns that they have no other choice. Scotty and Sulu agree and they go to work.
Magen informs Devna and Xerius of the new plan. The Orion woman fears for their safety, but Xerius reminds her that it is not against their laws to try and escape. He refuses to impede them even if they may die.
Kirk and Spock meet with their opposite numbers and Kor agrees to the plan. As they agree to start work immediately, a surprisingly enthusiastic Spock puts his hands on both Klingons' shoulders and admires their spirit of cooperation. Once Kirk and Spock leave, Kor assumes that Spock has become deranged because of passage into the pocket universe. Kaz wonders why Kor is working with Kirk, and the captain admits that he has a plan for the Enterprise
to disintegrate once they escape. He tells Kaz to make it so and the science officer assures him it can be done.
The two ships link and begin coordination efforts. Gabler brings two Klingons to the bridge and informs Kirk that he found the Klingons near the dilithium vault. The Klingons claim that they were lost and Spock comes over, hugs both of them, and insists that it must be a mistake. He leads them to their work area while Kirk looks on, surprised. Once Spock leaves, McCoy worries that the Vulcan isn't acting normally. Kirk agrees to talk to his friend. Later, Kirk points out that Spock is the only one who can engineer their escape, and asks about his recent behavior. Spock explains that he has used the two opportunities to touch the Klingons and briefly mind-meld with them. He has detected indications that the Klingons plan to sabotage the Enterprise
, but has no specifics. Kirk puts security teams on duty around-the-clock watching any and all Klingons.
On the Klothos
, Kaz created an explosive device that will detonate three minutes after they pass through the time barrier. Kor has a female officer, Kali, take the device.
That night, the Enterprise
hosts a party for the Klingons and the Elysia residents. Devna performs for them and admits that she wishes she could go back to Orion once more. When Kirk offers to take her, Devna says that they have all tried to escape and failed, and accepted their life in Elysia. Meanwhile, Kaz picks a fight with McCoy when he invites Kali to dance. Kaz draws a disruptor but Xerius freezes his weapon and orders Kaz, McCoy, Kirk, and Kor to the council chamber to face charges. Meanwhile, Kali slips away and plants the explosive device in the computer room in the warp control panel.
In the council chamber, Xerius finds Kor and Kaz guilty and proposes to freeze the Klothos
for a century. Kirk speaks up, pointing out that freezing the Klothos
will punish the Enterprise
as well by preventing their joint escape attempt. Xerius warns Kirk that they will fail but Kirk insists that while Elysia may be a perfect place, home is where they belong. The Romulan releases Kor into Kirk's custody and wishes them luck.
The next day, the two ships begin their joint maneuvers. As they accelerate to Warp 6 and beyond, Magen telepathically detects the Klingons' sabotage attempts. Xerius contacts Kirk and warns him, and Spock and Scotty run to the computer room. Meanwhile, the two ships approach the barrier. Spock finds the explosive and tosses it into an ejection chute. The two ships penetrate the barrier and emerge into normal space, and then part. The explosive goes off between the two ships, and Kor radios back to the Klingon High Command, taking full credit for their escape. Kirk says that it doesn't matter: their freedom is what counts.