The episode begins with Captain Archer in his ready room trying to have a friendly conversation over breakfast with Lt. Malcolm Reed, in an attempt to get to know him better. Reed however, being unused to this level of informality with superior officers, remains reserved and formal, and tries to focus on work related issues.
Meanwhile, the Enterprise begins to orbit an uncharted and seemingly uninhabited planet for closer observation. Its proximity however triggers a cloakedmine, heavily damaging the ship and flooding Sickbay with injured crew members. Among the injured is Ensign Hoshi Sato. Soon, another cloaked mine is detected as it attaches itself to the hull, but it doesn't immediately detonate for some reason. With the core already damaged, a further detonation is feared to destroy the impulse manifold and therefore totally disable the vessel. Lt. Reed then performs a spacewalk in an EVA suit to try to disarm it. As a backup plan, Archer orders Trip to prepare to detach and jettison the affected section of hull plating.
Initially Reed's efforts seem to be working, but as he defuses the mine, an alien vessel decloaks, and after a failed attempt at communication, it fires warning shots at the ship. Mayweather assumes manual control and steers the ship carefully out of the minefield. Meanwhile, during the maneuvers, a jolt accidentally activates another magnetic grappling arm that impales Reed's leg before attaching itself to the spaceship's hull, thus pinning him down. Captain Archer dons an EVA suit and exits in order to disarm the mine under Reed's direction. After administering a painkiller, they speak their thoughts frankly as they work, in contrast to their earlier meeting.
The Enterprise then makes first contact with the Romulan Star Empire when two Romulan Warbirds decloak and demand that they jettison the mine with Reed attached. Knowing that any attempt to cut the arm would set off the mine, Reed becomes insistent on sacrificing himself to save the Enterprise, and Archer has to stop him committing suicide at one point. Archer returns to the ship and requests two shuttle hatches from a puzzled Commander Trip Tucker, also ordering him to detach the hull plate as planned. As the plates and attached mine float off, he cuts the spike holding Reed. This arms the mine, but as Reed and Archer drift away from it into space, they are able to shield themselves from the resulting explosion with the shuttle hatches. The Enterprise then collects them before warping away from the armed Romulans.