Evil Acts is a one-shot adventure. You'll need the core book to run it, but it should be a good way to introduce it to a group, run at a game night or even a con.
From the blurb:
The play's the thing... or is it? Something fishy is going on at the local playhouse. A production of the Tempest has a bigger budget than makes sense -- and some surprising special effects. Could it be that there's something more to this than the grand final retirement performance of a talented actor? Lord, what fools these mortals be!
Evil Acts is a Dresden Files RPG casefile, a one-shot mystery-adventure intended for 3-6 characters at the "Chest-Deep" power level. Customizable, pregenerated characters, a mix of mortals, practitioners, and more, are provided with sheets and power details.
Whether as performers, audience members, or something else, the characters are drawn into a complicated web of theatrical sleight-of-hand and supernatural power politics. Will they unravel the mystery of Prospero's performance before the final curtain? Or will it be curtains for everyone?