Joss Whedon and David Greenwalt's Angel spent its first year establishing a workable premise, ensemble, and, most importantly, tone. Newly spun off from Buffy the Vampire Slayer, the WB network's zeitgeist-capturing (or, in Buffy-speak, "zeitgeisty") teen horror-comedy drama, Angel began its run as a tongue-in-cheek adventure series. In the pilot, "City of Angels," a chance meeting between depressed vampire-with-a-soul Angel (David Boreanaz) and fellow Sunnydale transplant Cordelia Chase (Charisma Carpenter) leads to the formation of Angel Investigations, a Los Angeles-based supernatural detective agency dedicated to "helping the helpless" -- for a nominal fee whenever possible. With his brooding good looks and his quest for redemption from evil, Angel provides the heroism and the hunkiness; money-grubbing would-be actress Cordelia, meanwhile, provides the laughs and more eye candy. Romantic angst and plot points come in the form of Doyle (Glenn Quinn), their half-demon ally. His direct line to the mysterious Powers That Be provides the firm with a steady stream of cases, while his attraction to the unattainable Cordelia makes up for the title character's limited romantic horizons. As the first season reached midpoint, however, the producers wrote Doyle out of the show and awarded his mysterious visions to Cordelia. At the same time, a new ally arrived in the form of ex-watcher Wesley Wyndham-Price (Alexis Denisof), another Buffy transplant. (This core trio would remain in place for the next three and a half years.)

Despite the cast changes, Angel retained its creature-of-the-week format for most of the season. Continuity came in the form of occasional flashbacks to Angel's demonic past; several Buffy crossovers, including a two-part story line involving Angel's friendship with rogue slayer Faith (Eliza Dushku); and the emergence of police detective Kate Lockley (Elisabeth Rohm) as the hero's reluctant ally and occasional nemesis. Future cast regular J. August Richards, as street-smart vamp-fighter Charles Gunn, arrived just as the season was wrapping up. More importantly, however, the writers began to realize the long-term plot possibilities of Wolfram & Hart, the demonic law firm introduced in the very first episode. The idea that the lawyers who run Los Angeles are not only literally evil, but also part of an interdimensional demonic conspiracy, helped shift the show's tone from light comedy and derring-do to heightened emotion and sustained suspense. A pair of warring Wolfram & Hart associates, conflicted Lindsay MacDonald (Christian Kane) and vampish Lilah Morgan (Stephanie Romanov), rescued the show's rogues' gallery from a procession of rubber masks. Meanwhile, the season finale saw the return of Darla (Julie Benz), Angel's vampiric consort, whose resurrection would drive the extended story lines of the next three seasons.