Archer receives news that A.G. Robinson, his old rival in the early days of the NX test program, has died. During a shuttlepod mission, Archer reminisces to T'Pol about the time he and Robinson were pilots competing for the honor of being the first to break the Warp 2 barrier.
Just as Enterprise is about to investigate what appears to be a dark matter nebula, Archer receives word that his old rival A.G. Robinson has died while climbing Mt. McKinley. Archer and T'Pol set off in a shuttlepod, and while the captain is uncharacteristically quiet, T'Pol finally gets him to open up about his complicated history with Robinson. Archer begins to remember the days when he and Robinson were part of the NX test program trying to break warp 2, while Admiral Forrest was a Commodore overseeing the program at Starfleet Command...
Both Robinson and Archer want the first flight — the assignment is particularly important to Archer, as his father designed the engine. Ultimately, Forrest gives the mission to Robinson. Though Archer is disappointed, he promises to give Robinson all the support he needs — later, at the 602 Club, he even raises a toast to his rival. Robinson confides that Archer didn't get the assignment because he's too by-the-book. Archer is trying to be a great pilot, but Robinson knows that Starfleet would rather have a great captain.
The next day, Robinson goes up in the NX-Alpha. Archer and Forrest man mission control as a few Vulcan advisors look on. The mission starts off well, but when the vessel encounters some problems, Archer and Forrest tell Robinson to abort. Robinson, however, is determined to break warp 2. He does, but the NX craft is destroyed. Robinson manages to get out just in time via an escape pod. The Vulcans are unimpressed with Robinson's stubbornness, and believe the NX vessel is faulty. Later on, Archer has drinks at the 602 Club with Forrest and a new acquaintance — Lieutenant Trip Tucker. Forrest reveals that the Vulcans have urged Starfleet to put the NX program on hold for an indefinite period of time ... and Starfleet has agreed. When Robinson shows up, he and Archer get into a heated argument about the mission — Archer believes Robinson is at fault, while Robinson blames the engine. The two men eventually come to blows, until Trip breaks up the argument.
After he cools off, Archer realizes that Robinson's words ring a bit true — there are problems with the engine. He and Trip run a few calculations and realize that they can make it work. They enlist Robinson in a plan to convince the Vulcans that the NX program is worth keeping on track. Robinson, however, doesn't believe that just talking with the Vulcans will work. He suggests they use the remaining NX vessel, the NX-Beta, to prove their point. The trio plans a night launch — Trip runs things from the ground while Robinson and Archer head up in the NX vessel. They succeed in getting off the ground without being noticed, but it's not long before they're found out. As Forrest orders them back to the ground, the two officers manage to get to warp 2.5 without any disastrous technical malfunctions.
Back on the ground, Forrest is furious (if more than a little impressed) and lectures his officers on their carelessness. Archer can't help but respond. He gives an impassioned speech about the importance of their actions, and how it will only help to further human exploration. The NX program continues, and several years later, Archer is awarded command of the Enterprise.
Back in the present day, T'Pol is intrigued by Archer's story. Just as he's finishing up, they discover the elusive dark matter nebula they were searching for. As it lights up the sky, even T'Pol can't help but be in awe. Archer notes that a sight like this is one of the reasons he and Robinson worked so hard to explore space. Back on Enterprise, T'Pol mentions that it is a human custom to name something you've discovered. She suggests dubbing the nebula "The Robinson Nebula." A moved Archer can only nod in agreement.