There are two dramas going on in Hector Tobar’s novel “The Barbarian Nurseries.” One is about a Mexican maid in a gated Orange County community who finds herself alone at home with two apparently abandoned boys. The other one I’ll get to in a minute.The boys’ parents have a fight about money -- Scott isn’t making enough to support Maureen’s entitled extravagance -- that ends, dramatically, with a push, a loss of balance and a shattered coffee table.Maureen takes the baby and heads for -- where else? -- a spa, leaving in such a rush that she forgets her mobile phone. Scott, unaware of her flight, grabs enough clothes to last until she has cooled down and he can slink home.The maid, Araceli, lives in a guesthouse on their property, and by the fourth day of their disappearance, all she knows is that her bosses have left her with two bewildered boys. The groceries are dwindling and she doesn’t drive. Nobody on the emergency phone list answers.She finds an old address for the boys’ grandfather, in a Los Angeles neighborhood that (though she doesn’t know it) has become a slum. So she sets off with them on a trip to a world they didn’t know existed.The parents return, find the house empty, panic and call the cops. Cue the media. The last of the novel’s three sections is titled “Circus Californianus.”The drama of the plot makes “The Barbarian Nurseries” a real page-turner. But the deeper drama -- for me, anyway -- is the battle inside Hector Tobar, between a talented novelist and an editorial writer (he is, in fact, a regular columnist for the Los Angeles Times) in a state of high dudgeon. Even late in the book it’s hard to guess which of them is going to get the upper hand.Every time Tobar stopped to bring in yet another character for yet another sociological walking tour into the melting pot of Southern California, I ground my teeth. He doesn’t have a gift for sketching in minor characters with the complexity of his major ones.His attempt to summon some empathy for a Mexican- hating bigot is as futile as Amy Waldman’s similar attempt with a Muslim-hating bigot in her recent novel “The Submission.” And I don’t think any of Tobar’s readers need a demonstration that the criminal-justice system is nicer to the rich than it is to undocumented aliens.On the plus side, though -- and it’s a big plus -- is Tobar’s altogether strange and wonderful heroine. Araceli Noemi Ramirez Hinojosa has spent four years working, dourly but efficiently, for Scott and Maureen. They don’t much like her, and behind her back they call her Madame Weirdness.They have no idea she spent a year at the Instituto Nacional de Bellas Artes in Mexico City. They first see “The Garbage Phoenix” -- a floating sculpture she painstakingly assembled from bits of their detritus -- only when they invade her guesthouse, looking for the boys.Araceli is proud, talented, bitter, bitterly funny, naive, imposing and severe. She’s unlike the hero of any novel I can remember reading, and she gives “The Barbarian Nurseries” an authority that none of its flaws can mar.