3:59

In this quasi–science-fiction novel, doppelgangers Josie and Jo agree to temporarily trade places after their mothers’ scientific experiments accidentally open a portal between their parallel worlds.

The situation soon spirals out of control as Jo’s mother (who also secretly traded worlds) attempts to make the trade permanent by destroying the portal. McNeil deserves credit for writing science fiction featuring women scientists. Josie and her lab partner, Penelope, as well as Penelope’s parallel-world other, Pen, all casually drop quantum-mechanics and parallel-universe theories and use the scientific method to understand the portal between their worlds. However, the devil is in the details, and offering little explanation of the scientific theories under discussion compromises the novel’s scientific tenor. Further stretching the science is the improbable existence of the laser that is used to create the portal. Readers must accept that an X-FEL laser, “one of the most high-tech, cutting-edge pieces of equipment in the world,” whose production at a lab required “millions in funding, a team of A-list scientists and engineers, top secret specs no one had ever seen,” was secretly recreated out of scraps in a residential basement. Also implausible is the half-baked insta-romance (true love after four days, really?) that fails to create romantic tension.

The patchy science, though hastily injected with romance, makes for an unsatisfying read.