Angel, Spike and Gunn travel to a surprisingly unusual hell dimension to free Lindsey and find out what he knows of the Senior Partners' ultimate plans. With Illyria's army defunct and her plans averted, the gang accepts her as a dubious ally. Wesley, volunteering to be her guide and mentor, falls slowly into depression and self-destruction. Meanwhile, the Senior Partners send a new, unstoppable force, a new liaison and businessman, named Marcus Hamilton, to find Eve, and Gunn makes an important decision in an attempt to protect his friends... and save his soul.

Parents bring their son to Wolfram and Hart to try to make sense of their son's superhuman abilities. Team Angel wants their assistance, but Angel refuses, because it's his son Connor. A demon is after Connor, but without his memories of his old life, he doesn't have much of a chance against the demon. True memories are revealed for Connor and a member of Team Angel

Illyria begins acting more strangely than usual. After she rescues Gunn from the suburban hell dimension, she begins displaying more power. After a hint from Hamilton, Wesley discovers that Fred's body is insufficient to contain Illyria's power, and she is about to explode. Meanwhile, Angel discovers that she is unintentionally leapfrogging through time, and uses it as possibly the only way to stop her. Also, Gunn begins to have suspicions about Angel being corrupted when he allows a demonic brethren to accept a pregnant young woman's baby as an upcoming sacrificial item.

The Team have reason to believe that Angel has been utterly corrupted with power when they find evidence that he has joined the Circle of the Black Thorn, the most evil of secret societies. Wesley, Gunn, Spike, and even Illyria discover some surprises when they urge Angel to side with the forces of Good again.

In the series finale, Angel reveals that his questionable moral behavior has been part of a bigger plan: to destroy The Circle of the Black Thorn and show the Senior Partners that the power of good can still make a difference. Wesley struggles with helping Illyria adapt to the world, scolding her for her attempts to take on Fred's form. As Gunn continues his quest of self-discovery, Lorne becomes more aware of the lack of happiness in the world. Harmony attempts to seduce Marcus Hamilton for information, Lindsey makes an important decision regarding his alliance, and Eve continues to deal with being mortal. As Spike comes closer to understanding the nature of heroism, Angel pays a visit to the one person he truly loves. On Angel's bidding, the gang goes out and spends each day as if it were their last...