(written from a Production point of view)
While Enterprise rescues three Denobulan scientists from a planet under a new xenophobic government, Dr. Phlox must treat a patient with racist views against his people.
While Ensign Hoshi Sato is visiting Doctor Phlox in sickbay, he hands her a tribble to hold for a moment, then takes it away from her and feeds the tribble to one of his other animals, much to Sato's dismay, though Phlox is oblivious to her distress. Sato leaves him a PADD she brought with her, an urgent transmission from the Denobulan Science Academy, which she intended to deliver to him. Once she leaves, Phlox reads the message and his facial expression grows grave.
Phlox, Captain Archer, Commander Trip Tucker, Lieutenant Malcolm Reed, and Ensign Travis Mayweather discuss the news in the situation room aboard Enterprise NX-01. The Denobulan Science Academy has asked Enterprise to find three of their geologists in the caves of Xantoras, as that planet has a new government which has just declared that all off-worlders must leave the planet within three days. Captain Archer sends Tucker, Reed, and Mayweather on the mission to retrieve the Denobulan scientists.
Since Mayweather has some caving experience, Archer asks him to get some gear together. He sends Reed and Tucker with him to comprise the away team. They have three days to find the scientists, or the Xantoran authorities will capture any off-worlders. Archer says if they don't find them within 36 hours, they must head back to the ship. On the ground, Mayweather leads the team to the nearest cave entrance from the scientists' camp site. Despite Reed's lack of finding any life signs, they continue and, at one point, rappel down.
Meanwhile, Enterprise overhears a communication between an alien transport ship and the Xantoras government. They are having critical problems with a reactor leak, but the Xantorans won't allow them to land. Archer decides to assist. Phlox manages the multiple patients coming from the ship, though one of the wounded individuals gives him pause. While Archer comes to get an update, he is surprised to find that this patient refuses treatment from Phlox.
Phlox explains to Archer outside sickbay. The patient is Antaran, the traditional enemy of the Denobulans with which they fought several wars. There was a lot of "bad blood" despite the last conflict happening 300 years ago. Phlox is adamant about respecting his wishes instead of simply sedating him to treat him. Archer, with the viewpoint of the Hippocratic Oath, orders him to treat the patient, but Phlox refuses, acting under Denobulan medical ethics, must respect the patient's wishes.
Archer intends to talk to the Antaran, Hudak, to make him aware of his situation and hoping he will allow Phlox to operate. Even if Phlox is able to overcome his first impression, the Antaran refuses to receive medical care from him, even at the expense of his life. Hudak encourages Archer to read about the history for his own context, noting that the Denobula's military tactics resulted in 20 million Antaran casualties. Archer does look up the information and then talks to Phlox. Phlox says the situation is complicated, due to the fact that Antarans are raised to fear and hate the Denobulans, and symmetrically, the Denobulans are raised to believe that Antarans are evil. Archer orders him to at least try to change the Antaran's mind by proving he is not what his people believe.
The away team seems to be making progress when finding some Denobulan equipment containing rock samples on their way down. Eventually, they reach the bottom of their descent and make their way through another tunnel, following interesting geological features for the best chance of finding the scientists. Then, in a cavern with a small ledge, the three make their way carefully along the wall. Reed, in front, loses his balance and the other two follow, being tied together. All three slide several meters toward a very deep hole. Reed and Tucker slide off the edge, but Mayweather catches a crevice with his leg, breaking it but stopping their fall.
Mayweather is in immense pain as he supports the other two while they try to swing to the wall to get hold of it and fasten themselves. Tucker, in the middle, barely makes it to the wall and fastens himself when Mayweather lets go of the rope. When they regroup, Tucker confirms the leg is broken with torn ligaments. Mayweather cannot keep up with them, so he stays behind.
Back on the Enterprise, Phlox goes to monitor the unconscious Antaran. The Antaran wakes and is immediately suspicious of Phlox. Phlox tries to make small talk, but Hudak relentlessly turns his comments against him, accusing him of some motive. Hudak suspects Phlox will kill him, but Phlox denies it and has had enough, going to other side of sickbay. Hudak provokes him, asking if he taught his children to hate Antarans like he was taught as a child. Phlox finally snaps, stating Hudak's people are the reason for the continued hostility, not his. Phlox leaves to go to the mess hall to cool down, and soon encounters T'Pol. He initially turns her away from his table, but then stops himself, asking about the repairs. She asks about the patient, which forces him to say he's dying to prove a point. He can understand his patient's point of view, through the way he was raised. Phlox did everything possible to prevent his children from having the education he had about Antarrans, to make them embrace other cultures. It becomes clearer why he is so upset by the irrational behavior of his patient. T'Pol compliments Phlox on his choice of parenting, but Phlox needs to leave.
Tucker and Reed must press on, and, after crawling through a particularly tight passage, eventually find the scientists and explain the situation with the Xantorans. However, despite the fact that it was the Denobulan Science Academy that made the order to recall them, the three Denobulans refuse to leave and go about their business.
Tucker and Reed are emphatic about not leaving without them, as they will be held responsible for not retrieving them. The three, however, are not concerned about the situation on the surface, saying that the government changes often and the situation will probably resolve itself by the time they are done. Also, the Denobulan Science Academy would accept the risk given what they've already achieved. They do admit that Tucker and Reed can be satisfied that they warned them, though. Tucker will not accept this, saying they've risked their lives to get to them, and has to threaten to tie them up and drag them before they finally decide to go.
Phlox talks to Hudak again about starting the procedure, and Hudak denies it again. Phlox decides to engage him, then, continuing their discussion earlier. He tells him about his own nightmares through his grandmother's stories about Antarans and the opposite way he raised his children, teaching them to judge for themselves. He also reveals that a rift formed with his youngest son, Mettus, who had been seduced by certain Denobulan groups that held on to those "archaic" beliefs. He then challenges Hudak to do the same and accept the treatment to set an example for his children. After some reflection, Hudak finally does, and calls Phlox to say he believes Phlox' sincerity and accepts treatment.
Tucker and Reed follow the scientists through the tight passage earlier, Tucker threatening to shoot again when one of the scientists pauses for another rock sample. Then, the cave rumbles and that gets everyone moving fast. They get to the rope again, and Reed suspects it is weapons fire. Indeed, the Enterprise detects the shooting and Archer hails the governor for answers, since they still have 90 minutes before his deadline. It appears neither his crew nor the Denobulans are the target. The old regime wants to fight back, not accepting the new government. Archer threatens the governor to stop firing or Enterprise will fire on his patrols. The governor relents, relieving Tucker and Reed to finish their climbing. Interestingly, the Denobulans can climb the particularly flat wall with great ease on their own with no gear. They retrieve Mayweather and reach the shuttle, with the loss of only a few more samples. They get back to Enterprise with a patrol ship on their tail.
Archer escorts Hudak to the transport, remarking the unfortunate circumstance that cut off his research. He tells Hudak that the three geologists they came to rescue are also on the transport, and asks if it's a problem. Hudak seems to have made clear progress in his perception of the Denobulans, as he is willing to share the same transport if they are. Archer has already talked with them, and they agreed. Late in sickbay, Phlox realizes that indifference to hatred also had its part to play in the continuation of the myths about the Antarans, and, he decides to try once more to reach his son by writing him a letter containing his recent experience.
"All it's capable of doing, really, is eating and breeding. The problem is they breed quite prodigiously."
- - Phlox, on a tribble he shows to Hoshi Sato right before feeding it to one of his pets
"The last cave I was in had handrails... a gift shop, and a snack bar."
- - Tucker
"A week's worth."
"Hmm. Five hundred meters."
"Waste disposal units."
"What are these for?"
"We take out everything we bring in."
- - Mayweather, Tucker, and Reed, before heading down to the caves on Xantoras
"What have you got?"
"Nothing but three Humans, one of which is not entirely convinced we're going in the right direction."
"Ah, make that two."
- - Tucker, with Reed, and Mayweather begin to enter the cave to find the Denobulans
"Isn't there a beginners' cliff we can start on?"
- - Tucker
"We're already behind schedule, ensign. We can't have you slowing us down. Thanks for getting us this far."
"You'll be alright."
"Respectfully, sir, it's not me that I'm worried about!"
- - Reed, then Tucker, to Mayweather
"I have tried to treat you with respect, but I refuse to listen to these insults. You're the reason we haven't been able to put the past behind us. You've kept this hatred alive. No Denobulan would want to be in the same room as you."
- - a heated Phlox, to the Antaran Hudak
"If you don't start moving in five seconds, I'm gonna take my phase-pistol and shoot you in the ass!"
- - Trip Tucker, to Yolen
- The style of backpack used by the Enterprise crewmembers in the caves was the Boblbee Megalopolis backpack.
- The containers carrying the Denobulans' rock samples were actually spacemaker pencil cases used by children for school.
- Phlox actor John Billingsley had mixed feelings about this episode. He noted that, while Phlox was created with a "Zen-like placidity", it was understandable that the writers would try to find some more conflict. However, he argued, "I think coming up with an episode where Denobulans were once war criminals, there was still this credible anger that had not been resolved, it seemed to me at least – and maybe some of the fans too – a little too jarring, a little too difficult to jive with what we knew about Phlox. A little bit had been alluded to in the first seasons, hearing in one episode that he'd been a medic in the Denobulan infantry. But there were aspects of that script that didn't quite work for me." Nonetheless, Billingsley believed the episode enabled himself and guest star Henry Stram to "find some good stuff." 
- John Billingsley additionally praised Director Robert Duncan McNeill, stating, "[He] did a terrific job in that episode keeping all from us getting overly mawkish." 
- The first and only appearance of a tribble in Star Trek: Enterprise takes place during the teaser of this episode.
Links and references
- Scott Bakula as Captain Jonathan Archer
- John Billingsley as Doctor Phlox
- Jolene Blalock as Sub-Commander T'Pol
- Dominic Keating as Lieutenant Malcolm Reed
- Anthony Montgomery as Ensign Travis Mayweather
- Linda Park as Ensign Hoshi Sato
- Connor Trinneer as Commander Charles "Trip" Tucker III
- Solomon Burke, Jr. as Billy
- Daphney Dameraux as an operations division ensign
- Evan English as Ensign Tanner
- Scott Hill as Ensign Hutchison
- Aldric Horton as an operations division crewman
- Aouri Makhlouf as a medical crewman
- Alexander Slanger as alien victim
- Cricket Yee as a science divsion crewman
- Unknown performers as
- Shawn Crowder as stunt double for Connor Trinneer
- Kortney Manns as stunt double for Anthony Montgomery
- Marty Murray as stunt double for Dominic Keating
2140s; ankle; Antaran; aragonite; Arboreal planet; bearing; bedside manner; botyroidal flowstone; breeding; calcite; childhood; Denobulan; Denobulan-Antaran wars; Denobulan Science Academy; Denobula; dermalin gel; Earth; firing squad; flex-cable; generation; gift shop; governor; handrail; hemostatic scan; Hippocrates; Hudak's children; imaging chamber; inaprovaline; intra-cellular regeneration; irons; kilometer; lava tube; ligament; medical book; medical ethics; meter; Mettus; osmotic eel; outlawed; patient; Phlox's friends; Phlox's terminal patients; Phlox's prejudiced grandmother; pitons; propaganda; ration packs; rock climbing; rope; scalpel; Shuttlepod 1; Shuttlepod 2; snack bar; speaker; speleothems; spelunking; tractosites; tribble; tribble homeworld; warp reactor; waste disposal units; Xantoras; Xantoras (planet); Xantoras military; Xantoras patrol ship; xenomythology
- "The Breach" at StarTrek.com, the official Star Trek website
- "The Breach" at Memory Beta, the wiki for licensed Star Trek works
- "The Breach" at Wikipedia
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