Check out the Defenders as they take on the 24th century! The future is truly wild!
This issue explains many long-standing seemingly random events that had never been explained from far back in the Defenders' volume, and also sets up the change to the "New Defenders" team that begins in the next issue.
The Elf shows the original Defenders--Dr. Strange, Silver Surfer, Hulk, and Namor--the Earth in the years 2387, in which it is nearly destroyed. He says it is their fault, and that is why they have been summoned to see the Tribunal. The Tribunal is an incredibly powerful group of beings that travel time and space like antibodies for the universe, fixing problems.
Beast, Iceman, and Gargoyle leave the Vision and Scarlet Witch's house after Cloud, Seraph, and Harridan are carted away by SHIELD. Beast is annoyed with not getting Vision and Scarlet Witch as teammates.
The Tribunal says they came upon the Earth of the future and were concerned because it had great potential, which was not fulfilled. Sending their agents (the Elves) back in time, they tried to find out what destroyed it. First they tried to kidnap several ordinary people who seemed to be involved (this explains the Elves' appearances in Defenders 25, 31, 38, and 46).
This didn't work, so they tried to learn about the Defenders, who seemed to be involved, eventually creating a trial-like process that called upon various witnesses like the Mutant force and Jack Norriss. (This explains the mysterious trial in issue 87). They then sent the Luann Bloom robot to learn even more, although she malfunctioned and began to believe she was human.
Finally they begin to explain what actually happened to the Earth: some time in the future, Dr. Strange finds a crashed alien ship. Inside, they are trying to heal their prince, using the energy of several humans' bodies. Strange stops them, but is captured himself.
Surfer, Hulk, and Namor come to rescue him. They do, but the aliens on the ship then all mystifyingly kill themselves. The reason why is explained next issue.