He meets Darla, his sire, in a dark alley and she offers him eternity. After becoming a vampire he kills his entire family, who thought he was dead (which, of course, is true to a certain degree). His sister believes he is an angel, which is where his nickname comes from.
Together with Darla he has his fun on a ship full of vampires. When they meet another ship, a young girls attacks him, but after a long and hard fight, he breaks her arms and she drowns in the sea. The next night she attacks the tavern in which the vampires stay. Obviously she cannot die and Darla and Angelus have a hard time getting rid of her.
Darla gets Angelus to her Sire, the Master. She wants that they obey him, but Angelus mocks the Master and the get thrown out.
At christmas he kills Daniel, a man who owes him money.
He meets Drusilla, the daughter of a miner. He's obsessed with her, drives her insane and in the moment when she wants to take the veil, he turns her.
After killing a Gypsie girl the Elders curse him with a soul. Darla bans him from their home and he wanders around, not being able to kill any himan being.
Angel comes back to Darla, Dru and Spike and wants to live with them (despite of his soul). However, Darla know that he has back his soul. She challenges him by offering him a baby. He can't kill the child (what a Nancy Boy), so he has to leave again.
Whistler finds him, sent by the Powers That Be and gets him to LA to see Buffy. Angel immediately falls in love with her and decides to help her.
On his first meeting with Buffy he gives her a silver cross. She doesn't know he's a vampire by then, but finds out soon.
On Buffy's 17. birthday Angel loses his soul (yay!). He turns on the Slayer and the Gang and reunites with Spike and Drusilla.
While awakening Acathla, a demon who swallows the world, Buffy fights him. At the same time Willow tries to redo the spell and succeeds. Angel gets his soul back, but Buffy has to send him to hell.
After spending about 100 years in hell he comes back to Sunnydale. But because he realizes he cannot be around Buffy he leaves Sunnydale after Graduation and moves to LA.
Doyle is his new connection to the Powers. At a party he meets Cordelia who wants to be an actress. With those three Angel Investigations is complete.
Fall 2000 L.A./USA
The law firm Wolfram&Hart brings back Darla as human. Angel starts to dream of her and finally finds out that she is back. He wants to help her (because she has a soul to save now), but Drusilla turns her again.