COUSINS IN THE TIME OF MAGIC, by Emma Otheguy; illustrated by Poly Bernatene

Time travel can be a funny thing. A risky one, too. When it wanders into the darker corners of history, the present isn’t the only thing that hangs in the balance. In Emma Otheguy’s imaginative and entertaining “Cousins in the Time of Magic,” though, the reward is well worth the risk.

The novel begins on a Monday afternoon like any other at its three adolescent central characters’ loving but scatterbrained aunt Xía’s house in Miami. Siggy, the oldest, is a budding influencer who’s recording a video for a hair product called Mirror-Shine Sheen. Camila, a bibliophile, is deep in one of her animal books. Jorge, the youngest and a thrill seeker, is climbing the garage roof on a dare from a pompous neighborhood boy he can’t stand. But when Jorge sees his aunt stashing a diamond-encrusted sword into a large clay pot in the front yard, everything changes.

Tía Xía, who works at the Latin History Museum, loves to lecture the cousins about how “history is alive” and how “the past speaks.” Only they didn’t expect it to speak this vividly.

They soon find themselves stumbling through the tinajón in the yard (where Tía Xía hid the sword) and emerging on an eerie, unfamiliar beach, far from Miami. Stranger still, three paper boats sit anchored near the shore, as if waiting to be discovered.

When Jorge spots the sword in one of them, he jumps into the boat, grabs it and slashes it through the air with glee. The others join him in the vessel and marvel at the weapon, admiring its blade and precious gems.

Siggy asks his cousins if they think their aunt knows about this mysterious island to which they’ve been transported. “She definitely knows,” Jorge answers confidently.

As if on cue — just as their boat’s anchor disengages, causing them to float out to sea — Tía Xía appears on the shore, climbs into one of the other boats and paddles out to them, entreating Jorge to give her the sword. When he holds it out to her, Jorge feels “a surge of electricity, like something warm and bubbly was flowing from his fingers to his toes.” After he lets go and Tía Xía takes it, a furious wind kicks up and carries her away from them.

Otheguy’s fantastical prose and charming characters keep the pages turning.

As the cousins sail off in a boat that looks “more like life-size origami than a seaworthy vessel,” they barely evade an ironclad warship firing at them in hot pursuit. Trying to make sense of their new surroundings, they encounter a runaway drummer boy named Alfonso who claims to be in the Union Army and is searching for his father, a Cuban-born Union spy who has been captured by Confederates.

The three learn that not only are they hundreds of miles from Miami, in Virginia, but they have also sailed through time, to 1862, smack dab in the middle of the Civil War. Soon they meet an enslaved boy named Oscar, whose father has been “sold on to Cuba,” who reminds them that “freedom matters everywhere.” And so the book’s title is both on the nose and perfectly endearing.

As it turns out, Tía Xía is not simply a frizzy-haired historian who sometimes disappears for long stretches and returns home covered in sand. She is also a time traveler on a critical mission to get the magical sword into the hands of Gen. Ignacio Zaragoza before May 5.

Zaragoza is best known for leading the Mexican Army to victory over French forces at the Battle of Puebla on May 5, 1862, now celebrated as Cinco de Mayo. These events are significant to the course of U.S. history.

After the cousins surmise that Tía Xía has been seized “by the same people who want to steal the sword,” the escapade becomes something of a rescue mission for everyone involved. The only way for the trio to save their aunt, help their new friends and return home is to restore the sword to General Zaragoza and, finally, bear witness to the Battle of Puebla.

Otheguy’s novel is deeply original, action-packed and brimming with historical richness and wit.

It is particularly satisfying to see how her characters change and grow on their journey, ultimately gaining a better understanding of their culture and its influence on the United States at large. She does a wonderful job of infusing the complexity of identity into the narrative while maintaining a welcome playfulness.

Lovely illustrations by Poly Bernatene — scattered smartly throughout — add a touch more magic to an already enchanting book.

COUSINS IN THE TIME OF MAGIC | By Emma Otheguy; illustrated by Poly Bernatene | (Ages 8 to 12) | Atheneum | 240 pp. | $17.99