As Kirk is having lunch in his quarters, a gigantic glowing sphere approaches the "Enterprise", filling the bridge viewscreen even at low magnification. Commander Balok identifies his ship as the "Fesarius", the flagship of the "First Federation", explaining that the destroyed cube was a border marker. Balok ignores Kirk's greetings and announces that he will destroy the "Enterprise" for trespassing into First Federation territory and destroying the marker buoy. He gives the crew ten minutes to pray to their deities. First Officer Spock obtains a visual of Balok, a blue-skinned humanoid with constantly shifting facial features. Bailey succumbs to hysteria, and Kirk orders him off the bridge. Dr. McCoy rebukes Kirk, arguing that Bailey's outburst was a result of Kirk putting too much pressure on him, and pointing out that he warned Kirk of Bailey's condition ahead of time. The argument inspires Kirk to try bluffing Balok. He tells Balok that the "Enterprise" contains "corbomite", a substance that automatically destroys any attacker, and claims he has little regard for the fact that the "Enterprise" would also be destroyed in the exchange. While Kirk awaits a response, Bailey asks permission to resume his duties, which Kirk grants. Balok demands proof of corbomite's existence, but when Kirk refuses, he does not destroy the "Enterprise". Instead, a small tug ship detaches from the "Fesarius" and tows the "Enterprise" deep into First Federation space, where Balok states he will intern the crew and destroy the "Enterprise". Intuiting that the tug ship's tractor beam cannot be as powerful as that of the "Fesarius", Kirk orders the "Enterprise" to engage the engines at right angles to their course. Just as its engines are about to explode from overload, the "Enterprise" breaks free. This apparently disables the alien vessel, as the crew picks up a distress call which its mother ship does not answer.