If you’ve never heard of Lake Bell, get cracking. She’s a live-wire. Often the best thing in silly movies (No Strings Attached) and stupid TV (Miss Match), Bell has kicked out the jams with her first feature as writer and director. It’s an exhilarating comic rush called In a World . . . and in it she spins inspired lunacy around the subject of, among other things like family dysfunction, sexual healing and female empowerment, voiceovers. You heard me. You’ve certainly heard trailers that begin with a male voice (Don LaFontaine dominated the field till his death in 2008) booming, “In a world . . .” as an intro of some florid sci-fi epic. Bell plays Carol Solomon, a struggling Hollywood vocal coach (she teaches Eva Longoria to do a Cockney accent) who wants to break into the lucrative, male-dominated field of trailer voiceovers. Her egotist dad Sam (a hilariously self-regarding Fred Melamed), who’s good at it and whose house she lives in, doesn’t want her infringing on his boys’ club. With the support of Louis (Demetri Martin), a sound engineer who’s attracted to her, Carol gets a shot at voicing the come-ons for a from-hunger girl-power quadrilogy called The Amazon Games. The guys in her field hate her for it, of course. Bell’s script, which won a deserved writing award at Sundance, inserts a subplot about Dani (Michaela Watkins), Carol’s older sister, and Dani’s boyfriend Moe (Rob Corddry) that’s not as irrelevant as it first seems. In fact, Bell the writer, director, producer and actress knows how to set a savvy trap. While we’re laughing, she pulls the rug out, making us see Carol’s world as a microcosm for the world every working woman lives in. That she does it with subtlety, humor and touching gravity marks Bell as a filmmaker to watch.