BOOK REVIEW / REVIEW : A Mother’s Mysterious Death Leaves Family in Shadows : AFTER LYDIA, <i> by Sandra Tyler</i> , Harcourt Brace, $22, 304 pages

Lydia has been dead for a year when this novel opens--killed by a train at a railroad crossing in an inexplicable accident.

She is survived by her daughters, Meryl and Vickie; her son, Warren; her husband, Blake and her 80-year-old mother, Ruth.

Vickie, the youngest member of the family and the narrator, has returned to their small Massachusetts town for a reunion party arranged by Meryl to celebrate their grandmother’s pivotal birthday, an event that no one but Meryl seems to want, least of all the honoree herself.

In contrast to her conventional sister, married just out of high school and already the mother of two, and her dreary older brother, Warren, newly separated from his wife of 20 years, Vickie is a bit of a maverick--”a bit” being the operative phrase.

For one thing, she has moved away from Lawton, where the family has lived for five generations, to create a life for herself in New York. For another, she had an affair at the age of 16 with a man twice her age.

Unlike her older sister, who settled into domesticity, Vickie was a college drop-out who has since flitted from one job to another, quitting her latest and best as an assistant designer at a publishing house just before driving up to her home town for her grandmother’s birthday.

Though not exactly looking forward to the visit, Vickie is eager to see her old lover, Kyle, an attachment that seems to have prevented her from embarking upon any others. Kyle was considered “unsuitable” by the rest of the family, though he was apparently the one who engineered the break-up.

A year after the fact, the family and Lydia’s closest friend, Gail, are still trying to make sense of Lydia’s death. The thought of suicide haunts them all, because Lydia was so well-aware of the dangers of the railway crossing that no one can imagine her straying into the path of an oncoming train.

Blake remains stunned, abandoning the practice of architecture to carve toys in the basement of Ruth’s house, and Ruth, once the most vivacious and public-spirited woman in Lawton, has allowed herself to slip into apathy. Querulous Meryl, her barely visible husband, Glenn, and depressed Warren do little to enliven the story.

Nothing actually happens until Meryl and Glenn’s 10-year-old daughter, Alex, disappears after hearing her parents argue. The day before the crucial birthday celebration, Glenn accidentally shoots one of Gail’s pet dogs, a misadventure that casts a distinct pall over the festivities, already made less than merry by Ruth’s abrupt departure from the party before the cake is cut.

“After Lydia” is distinctly non-linear in structure, with continual shifting in time from past to present as Vickie attempts to solve the mystery of her mother’s death. A few faint clues do emerge from conversations between the narrator and the rest of the family, but it is Lydia’s friend, Gail, who eventually provides the most telling insight into Lydia’s state of mind.

As is usual in such novels, there are home truths and unsettling revelations, but Lydia, the woman at the core of the story, remains not only absent but elusive. Ultimately, the only memorable character is the octogenarian Ruth, who has purchased a non-operational and clearly symbolic Thunderbird that she keeps in the yard as a sort of adjunctive living room.

By the end of the book, she is able to slap the dashboard, slam the door and say, “Silly old car.”

Vickie, however, is left with her fingers interlaced, “trying to find some comfort in the feel of her own clasp.” The novel will apparently be her next step.