It seems to be that the bigger the family, the less that gets said between its members.

Such is the dilemma of Jenn Ashworth's ambitious third novel, The Friday Gospels. Meet the Leekes, an aptly named Lancashire family aspiring to grow in their Mormon faith, but who privately struggle to meet the religion's expectations. On a Friday in August, middle son Gary returns home from a two-year mission in Utah. His homecoming is the tipping domino in a line of plot twists, which eventually sees all the family secrets come spilling out. Told in the family's five voices, or "gospels", this novel explores the shame and guilt that can arise in tight religious communities.

Chosen by BBC's The Culture Show as one of Britain's 12 best new British novelists, Ashworth was born in Preston in 1982 and raised as a Mormon. The novel begins with the family up at dawn on the morning of Gary's homecoming. Wheelchair-bound matriarch Pauline chirps at the rest of the family that tonight will be a "special dinner, us all here". Oldest son Julian complains he has too much to do at the garage where he works. Youngest daughter Jeannie insists she has hockey after school. And father Martin reassures Pauline that all will be fine before driving Jeannie to her morning Mormon classes which start at the dedicated hour of 7am.

Each member of the Leeke family is unhappy in their own way. Never fully fit after a difficult childbirth, and refusing to see a doctor about her incontinence and mobility troubles, Pauline endures a humiliating experience at the supermarket. Julian hasn't been to church in 10 years and is plotting an elaborate escape from the community. Fourteen-year-old Jeannie has been hiding her pregnancy for four months. Martin becomes besotted with Nina, a fellow dog-owner whom he sees daily while walking his dog Bovril. And stuttering Gary, home from his mission, must admit that he didn't manage to convert a single person in Utah. Some of these problems are clichéd – teen pregnancy, an older man fancying a younger woman. But the presence of these issues invites the Mormon view, an area where Ashworth illuminates her audience.

In fact, it is Ashworth's portrayal of Mormon traditions and beliefs that gives the novel an intuitive and humorous edge. Some scenes are memorable for their ironic or embarrassing content. The Mormon emphasis on chastity before marriage sees an uncomfortable Jeannie at her religion class being presented with a prettily iced cupcake as a metaphor of her virtue. As part of a lesson on today's casual attitude towards sex, she is told by Brother Fletcher to give the cupcake to a boy in her class. The church leader encourages the boy to eat the cake: "Have the cherry as well. Why not?" On the plane back to England, Gary makes a last-ditch attempt to convert the man sitting next to him: "I wanted to bear my testimony to you, s-sir. I wanted to tell you that I know, without one shad-shad-shadow of a doubt, that what I'm about to tell you is true." Though laced with stumbles, Gary's plucky entreaty illustrates the significance of conversions in Mormon culture.

It is hard enough writing a novel in one point of view, not to mention five. Here Ashworth stretches herself a little. There's not much difference in the style of voices, so the bold and capitalised names announcing each family member's narrative is a helpful touch. Generally Ashworth employs a similarly anguished, fragmented and near stream-of-consciousness style for each of them. Of the five narratives, Pauline's bossy but pleading voice and Gary's humble and desperate tones seem to be the most defined; the personalities of Jeannie, Martin and Julian are less explored by comparison.

However, by the conclusion the Leeke family is firmly united. Perhaps it's ironic that in a novel about religious practices, a violent episode brings the family together and allows them to be emotionally honest with themselves. Burdened by the weight of their secret, one of the Leekes finally snaps. And as Ashworth clearly points out, it is not faith but family that has the power to save.

The Friday Gospels

Jenn Ashworth

Sceptre: £17.99