Think of “Accidentally on Purpose” as “How I Knocked Up Your Mother … Who Decided to Keep the Baby.” Jenna Elfman remains charming enough, though she’s morphed from the free-spirited Dharma into a more grounded and responsible movie critic (oxymoronic, yes) who beds a younger man — yielding unintended consequences, if not much hilarity. The pilot is breezy enough, and there are solid supporting players, including Ashley Jensen and Grant Show. Those ingredients, however, are thus far more promising than what first comes out of the oven.
Having broken up with her dashing but commitment-phobic boss (Show) after he balks at proposing, Elfman’s 37-year-old Billie winds up in bed with a twentysomething dude named Zack (Jon Foster). At first giddy and a little horrified, after a few trysts that she likens to “young candy,” Billie quickly discovers (this is one fast-moving half-hour) that she’s pregnant; Zack, an aspiring chef in need of a place to stay, insists he wants a role in the baby’s life.
Thus begins a sort-of clash of not-quite generations, with Zack and his slacker friends entering Billie’s world. The twentysomething guys provide something of a fit with the “How I Met Your Mother” and “The Big Bang Theory” components of CBS’ Monday comedy block, though nobody will confuse these nitwits with the genius variety.
Jensen (“Ugly Betty”) is consistently good company as Billie’s pal, Lennon Parham has moments as the protagonist’s bubbly sister, and Elfman gets to widen her eyes a lot in response to big surprises.
At the very least, the pregnancy plot offers reasonably ripe territory to mine in a semi-serialized way, although like the whole backward-love-story template (pregnancy first, relationship to follow), the key will be at what pace all that develops. On the plus side for the show, with CBS consolidating its strength from 9-10 p.m. by moving “Big Bang” behind “Two and a Half Men,” the network can give “Accidentally” time to gestate as long as it doesn’t completely squander what should be “Mother’s” modest lead-in.
Of course, the plot outlines are something of a fantasy, otherwise Zack would head for the hills when Billie gives him the opportunity, and the San Francisco newspaper employing her would lay off half its staff, starting with the movie critic. Fortunately, comedies where unplanned pregnancies become the source of laugh lines are mercifully immune from such bummers.