Inside Cats Lair, the ThunderCats receive a distress signal from the space-liner Vertus which is in the Sea of Stars, six light years from Orion. Lion-O, Cheetara and Snarf take off in the Feliner to assist the space-liner.They soon reach the enormous spaceship, Vertus, which is drifting right on the edge of a Black Hole. Lion-O and Snarf board the ship but do not find anyone on board. While exploring the ship, they come across cups of hot coffee laid out on a table. Lion-O takes a whiff of one of the cups and immediately loses consciousness. Snarf also passes out by inhaling the fumes from the spilt coffee. At the same time, the Feliner gets fired upon by laser beams from the Vertus but Cheetara manages to avoid them and zooms away back to Cats Lair to get help.When they regain consciousness, Lion-O and Snarf find themselves prisoners of the ship's captain, Shiner, who is now in possession of the Sword of Omens. Just then, Mumm-Ra materializes and reveals that it was he who hired Shiner in order to obtain the sword. Mumm-Ra then casts the sword into the Black Hole after which Shiner's crew chain Lion-O and Snarf in the reactor room of the ship and force them to pull Boron rods.Meanwhile, Cheetara returns in the Feliner with Panthro and drops him on the Vertus. Panthro sneaks into the spaceship and frees Lion-O and Snarf from the reactor room. The three then neutralize Shiner's crew and take over the ship. Panthro then sets the course for the Black Hole, much to the shock of Captain Shiner.The Vertus enters the Black Hole which turns out to be a giant force field, filled with debris of old spaceships and satellites. They then come across a super power station which is controlled by a computer known as NEPTUNE, the Navy Engineers Power Tower Under Nuclear Energy. The artificial intelligence imprisons the ThunderCats and Shiner in an impregnable Titanium room.Just when all seems lost, Jaga appears and reminds Lion-O that the Eye of Thundera only sleeps until needed. Lion-O then summons the sword to his hand and uses it to break out of their cell. Panthro reverses the magnetic polarity of the power station before he Lion-O, Snarf and Shiner board the Vertus. The reversal of the magnetic force causes everything to be repelled out of the Black Hole including the Vertus. As the ship emerges from the Black Hole at break-neck speed, it hits an asteroid which badly damages it. Shiner orders the three ThunderCats to abandon ship while he chooses to go down with it. Luckily, Cheetara spots them and picks up Lion-O, Panthro and Snarf in the Feliner. While the ThunderCats assume that Shiner perished with his ship, he is shown to have escaped safely in a smaller spaceship.