LIKE EVERYTHING ELSE these days, children's mysteries are somewhat trendy. Two of these reflect the current revival of interest in Dracula. Another seems to have been inspired by the adventures of young Samuel Bronfman II, heir to the Seagram fortune, who was accused of engineering his own kidnapping.

In the best of the group, The kidnapping of Christina Lattimore, the heroine is a junior at a Houston private school. Her grandmother is a tough lady who runs the oil business he late husband started; her father, a "religious maniac," is a lay preacher who is always asking people if they're saved. (In one of the few flashes of humour in the book, one Christina's friends answers this impertinent question with a long rigamarole about the time Coast Guard saved her when a riptide pulled her surfboard into the Gulf of Mexico.)

Shortly after the book opens, Christina is kidnapped. Nixon makes the abduction credible and builds suspense beautifully. But when Christina is released, she finds that she is suspected of having arranged the snatch in return for half the ransom which her grandmother has paid. The rest of book is concerned with her attempts to clear herself and to come to terms with her life and her family.

Christina is splendidly realized character. Her hopes and fears and her relationship with her parents are completely believable, but far from predictable. A few details of the plot are carelessly sloughed over, and the solution is not totally satisfying, but Nixon does a good job of strewing red herrings about. All in all, a first-class job.

Bunicula is laden with whimsy. The narrator, a dog named Harold, plays Watson the Holmes of Chester, the cat. The villain is Bunnicula, a rabbit that Harold's owners found on a seat in a movie theater where Dracula was showing.

Chester and Harold discover that Bunnicula sleeps all day but escapes from his cage at night. Then they find white carrots and suspect Bunnicula of sucking color from them. Chester, who reads a lot, untangles it all. Despite the whimsy, its pretty entertaining.

The case of the Phantom Frog also owes a debt to Dracula . This time the mysterious stranger is Bela, a Hungarian boy whos come to town to live with his aunt. The McGurk Organization, a group of 10-year-old detectives (featured in such previous Hildick titles as The Case of the Secret Scribbler ), is called in. At first, they suspect Bela of being a Werefrog, but they soon discover the Real Truth.

More in th classic pattern of Nancy Drew is the plot of Mystery of Eagle's Claw. Its heroine is Quail, daughter of a Vietnamese mother and American soldier, who has been adopted by another American couple and brought to his country. When both her adoption parents die, Quail is sent to her adopted father's aunt, Bouise, who runs an inn in Maine.

The story has lot of going for in a locked room, a missing ring, a girl who casts spells, a mysterious eagle's claw talisman, and an albino dog who is friendly on Sundays but a fierce killer on a week-days. What it lacks is good writing, a tight plot and plausibility. Nonetheless, it demonstrates the strength of the genre, for the time-honored ingredients, such as the locked room, have an appeal that offsets the flaws.