Laura Zigman offers a modern take on the bonds of sisterhood in "Small World," a novel about siblings whose difficult childhood has morphed them into emotionally challenged adults who lack the ability to have normal relationships.

Zigman is a noted raconteur of stories about families. In "Separation Anxiety" and "Dating Big Bird" she shows a rare ability to write freshly and empathetically about our need for strong connections. "Small World" may be her most personal work. The story of a family that includes a child with disabilities is dedicated to her sister Sheryl who died when she was 7, and Laura was 3.

Joyce and Lydia Mellishman, 50-ish divorcees, are living together in Joyce's Cambridge apartment after Lydia, who lived in Los Angeles for 30 years, decides to move back East. Joyce sees this as a rare opportunity to get to know her enigmatic sister and resolve family issues that marred their childhood.

And Joyce really needs this chance. She works from home, digitizing photos for family legacy projects. She's fascinated by what she thinks are "normal" families, and wonders "How come I didn't get to grow up like that?" But Joyce knows the answer, as does Lydia: Once there were three Mellishman sisters, but Eleanor, who had cerebral palsy, died when she was 10.

When she's not living other people's lives through their photos, Joyce is lurking in "Small World," her neighborhood's social networking site, turning posts about lost cats and missing wedding rings into prose poems. For Joyce, dwelling in "Small World" is "easier than being in the real world." With sensitivity and wit, Zigman uses Joyce's isolation to spotlight the insular world of the internet where lonely people turn, more and more, toward an artificial life.

Socially awkward Lydia, like Joyce, knows that when Eleanor was alive and after she died, she and Joyce were always "silent bystanders" in their parents' lives. Their mother ignored them while Eleanor was alive, and after she died, Louise turned her attention to helping other families like theirs. Joyce realizes her parents "didn't seem to understand that we were there, too."

Joyce and Lydia have a chance to reckon with the past, but when new, noisy neighbors move into the apartment above them, they focus all their energy on the mysterious sounds coming from above and delay, consciously or unconsciously, confronting the multilayered grief that has stunted them since childhood.

Zigman's tenderly told novel is a realistic rendering of what it's like to care for and love a disabled child, and the toll that love takes on parents and siblings. It's also about the bonds that sisters share and how, in the case of the Mellishmans, unresolved grief nearly breaks them. As grim as this novel sounds, it's laced with the promise of a brighter future.

Carol Memmott is a writer in Austin, Texas.

Small World

By: Laura Zigman.

Publisher: Ecco, 304 pages, $27.99.