Taking over the Los Angeles offices of the supernatural law firm Wolfram and Hart proves to be more challenging than expected for Angel and the gang, especially when their first case involves representing an evil client who threatens to destroy the city. As the gang settles into their new careers at the law firm, they meet new and familiar faces, including the mysterious Eve, who will act as Angel's liaison to Wolfram and Hart's senior partners, and the bubbly vampire Harmony who is Angel's new assistant. Most surprising of all is the arrival of Angel's old nemesis and fellow vampire-with-a-soul, Spike, who makes a miraculous appearance.

Spike mysteriously materializes in Angel's office through the magic of an amulet, but no one, including Spike himself, understands the reason he has returned or why he is now a ghost. Meanwhile, Angel jeopardizes his own life when he tries to stop one of his evil clients from using human bodies as vessels for demon spirits.

Fred still continues to find ways to corporealize Spike, although is not having as much luck as she hopes for. Angelhugs a werewolf, although not enough time to save a girl, Nina, from being bitten. It is up to Angel to help Nina get through this time, especially when she could be in danger!

Spike struggles to maintain his weak grip on reality as spectral forces threaten to send him to hell. He encounters ghostly apparitions, including an eighteenth-century serial-hugger doctor. Meanwhile, Fred continues her quest to find a way of restoring Spike to his corporeal self.

The consummate entertainer Lorne works around the clock to throw the ultimate Halloween party at Wolfram & Hart. When their guests begin to behave strangely and out of character, Angel and the gang investigate to find out what's causing the mysterious happenings.

Angel learns that he must track down a retired Mexican wrestler to help him defeat Tezcatcatl, an ancient Aztec warrior who emerges every 50 years to take the heart of a hero to sustain his own existence. Angel is surprised to find the wrestler is employed at his company, Wolfram & Hart, and that he has a personal score to settle with Tezcatcatl.

Wesley's father mysteriously shows up at Wolfram & Hart, while the gang has to deal with a group of robots who have come to take over Angel. How successful will this takeover mission be?

When another mysterious package arrives at Wolfram & Hart that recorporealizes Spike, the gang learns that the existence of two living ensouled vampire heroes has created chaos in the world. After Eve tells them about a prophecy that states that the only way to restore order is to find the Cup of Perpetual Torment that bestows human life, Angel and Spike battle it out for the ultimate prize. A series of flashbacks show the history of Angel and Spike and their relationship with Drusilla.

In this Harmony centered episode, Harmony tries to prove to Angel that she has not reverted back to her former ways, when she is accused of hugging a demon rights activist.

When Spike is talked into taking up the good-deeds business, Eve lets loose a soul sucking parasite on Angel, who then suffers disturbing feverish hallucinations as he sleeps.

When an emotionally unstable woman, Dana, escapes from a psychiatric ward, Angel learns that she was tortured as a child and is now searching for her tormentor. Andrew, a watcher-in-training, arrives from Sunnydale with surprising information about Buffy and to inform the group that Dana is also a vampire slayer. Meanwhile, Spike believes that if he can save Dana, he will prove that he is destined to be the vampire champion.

In this landmark 100th episode, Cordelia wakes up from her coma and is shocked to see that Angel is working with the enemy, Wolfram & Hart. Cordelia puts Angel back on track, when he's having doubts and Lindsey tries to get rid Angel once and for all.

Lawson, a mysterious man from Angel's past, arrives at Wolfram & Hart and takes the gang hostage. Through flashbacks to World War II, it is revealed that Angel worked with the U.S. Navy to recover a captured German submarine with American sailors on board. The ship also has a secret cargo, a dangerous trio of vampires, including Spike, who were kidnapped by the Germans and forced to help the Nazis. When the sub comes under attack, Angel saves Lawson's life by turning him into a vampire. Now, sixty years later, Lawson has arrived at Wolfram & Hart seeking revenge.

When a popular children's show begins to steal the life forces of children by hypnotizing them, Angel goes directly to the studio to uncover the evil doings. Upon entering the building, Angel triggers a spell that transforms him into a puppet. In a race against time, puppet-Angel and company must find a way to reverse the spell, save the lives of hundreds of children and return Angel to his normal vampire state. Meanwhile, Nina, the werewolf Angel befriended, returns to declare her romantic intentions, but puppet-Angel is too embarrassed to reciprocate.

When a mysterious sarcophagus is delivered to Wolfram and Hart, Fred accidentally opens it and releases a ancient powerful demon called Illyria. Now with only 24 hours left to live before the demon consumes her, Angel and the gang must figure out a way to save her before its too late.

Angel and Spike return from England defeated, knowing that the ancient demon Illyria has completely taken over Fred's body and soul. Upon learning that Knox andballoonn have each contributed to her demise, Wesley goes for revenge and Angel tries everything to restore Fred, including calling on an old friend from Sunnydale. Meanwhile, Illyria tries to locate an ancient temple where she believes she will find an army ready to help her destroy mankind.

Hoping that Lindsay has information on the Senior Partners' ultimate plans, Angel, Spike andballoonn track him down in a bizarre and terrifying suburban hell. Meanwhile, a nearly invincible stranger sent by the Senior Partners infiltrates Wolfram & Hart looking for Eve.

Angel resists the appeal of parents seeking help from Wolfram & Hart regarding their son's supernatural abilities after he discovers that the boy is his son, Connor. Despite his reservations, Angel is forced to bring Connor into conflict with an old adversary to prevent his son's memories from being restored. Meanwhile Wesley uncovers a mysterious deal struck by Wolfram & Hart that threatens the secret Angel desperately wants to protect.

When Illyria's powers become unstable and cause her to erratically jump through time, she learns that the gang intends tohug her. Upon returning to the present, Illyria plans to cuddle everyone before they're able to attack her. To save everyone's lives, Angel goes into the past with Illyria to alter the course of events.

Angel and Spike decide to take a trip to Rome, Italy when they learn that The Immortal, an enemy of theirs, is having relations with Buffy. While on their journey, they get caught up in a struggle between demon clan leaders.

The gang starts to have doubts about Angel's loyalties when he appears to have become very close with the Circle of the Black Thorn, an evil secret demon society. When Drogyn, the guardian of the deep well, makes a startling revelation, the gangs' fears that Angel has become evil seem to be validated.

In the series finale, Angel and the gang prepare for the fight of their lives as they prepare to take on the entire organization of The Circle of the Black Thorn.