Stella and her Australian half sister, Josie, have always happily spent their summers together on the Jersey shore with their twice-divorced, shared dad.This year things threaten to be different since Stella is fully embracing her almost-high school status but Josie lags behind, not quite so interested in boys, bonfires, and the hope for a kiss or two. Stella would willingly give up some of their childish rituals, but they still hold a strong attraction for Josie. Although this familiar dichotomy could have been the sole focus of the tale, Callaghan adds spice. Both girls are surprised to discover that their favorite water-ice shop has been replaced by a trendy new smoothie place that seems to be concealing a dark secret. After some determined sleuthing they discover an evolving environmental disaster that endangers the sea but also (a trifle implausibly) their beloved boardwalk. The tale is related in the girls' fairly similar alternating voices that recollect a busy week, interspersed with their lengthy interviews at the police station a few days later. These gradually reveal the excitement the two stir up. The bemused, deadpan response of the police detective adds a touch of slightly ironic humor. The bad guys are mildly nasty, and the hint of innocent romance experienced by the characters (all seemingly white) is sure to please preteen readers.Altogether, a fine choice to bring to the beach. (Mystery. 9-12) Copyright Kirkus Reviews, used with permission.

Gr 4--6--Each summer, half sisters Josie and Stella spend several weeks with their father at the New Jersey shore. Since the girls live with their mothers on opposite sides of the world (Josie in Australia, Stella in New York City), it's the only time they get to see each other. It has always been a special time, and the girls put mementos from their adventures in a box that they hide in the sand under the boardwalk. This summer, however, something has changed. Stella wants to do different things, and Josie passionately boycotts the new Smoothie Factory, which replaced Water Ice World. Next, they discover someone has stolen their box of memories, and when Josie suggests starting a new one, Stella only half-heartedly agrees. Then, what's different suddenly becomes more nefarious as the girls (along with their friends) become entangled in a web of sinister actions that could endanger both humans and sea life at Whalehead Beach. The cast of characters features blended families, and the environmental story line is both relevant and timely. Callaghan creates great suspense by having each chapter alternate between the recent past (within a month) and the present, where Stella and Josie are being interviewed by a police detective. VERDICT This fast-moving story will appeal to young teen and tween readers who enjoy books with an oceanside theme, and its spirited heroines will resonate with those who dream of making a difference in the world.--Anne Jung-Mathews, Plymouth State University, NH

Stella and Josie are half sisters who only get to see each other during summer vacation at the Jersey Shore, where they hide their special scrapbook under the boardwalk. This summer, however, Stella is more interested in boys and bonfires, while Josie wants to protest the smoothie store that replaced their beloved flavored-ice shop. When the girls--using powers of deduction and Josie's interest in marine biology--discover that the structural integrity of the pier is becoming unstable due to illegal dumping that appears connected to the smoothie shop's "secret" ingredient, they concoct a plan to save the boardwalk. Callaghan (Lost in Paris, 2015) tells a story that is part mystery, part family drama, with chapter narration alternating between the two sisters as they chronicle their actions at the boardwalk through an interrogation by the local police. Readers will easily relate to both sisters and be excited by a possible sequel.