The house of secrets
Nina Bawden
While staying with their aunt in an English seaside town, the Mallory children find a secret passage into the mysterious old house next door, where their efforts to help a strange girl lead to trouble and adventure.

by Joel Stewart (2008)
"Stanley Wells is sleeping in the caravan at the bottom of the garden of his new house. He awakes at the sound of an odd whooooomphing noise and goes to investigate. There appear to be new trees in the garden - very odd. And now his mum and the twins are missing - could these things be connected?" -- Publisher details.
Nina Bawden
While staying with their aunt in an English seaside town, the Mallory children find a secret passage into the mysterious old house next door, where their efforts to help a strange girl lead to trouble and adventure.
Carolyn Keene
The Dean of Emerson College enlists Nancy to investigate the thefts of a valuable substance being used in a top-secret experiment. But when Nancy discovers that the experiment involves biological mutations, she knows she must find the culprit before the lives of everyone on campus are endangered.
Donald J. Sobol
Leroy Brown is back in the next six books in the Encyclopedia Brown series. As Idavilles ten-year-old star detective, Encyclopedia has an uncanny knack for trivia. With his unconventional knowledge, he solves mysteries for the neighborhood kids through his own detective agency. But his dad also happens to be the chief of the Idaville police department, and every night around the dinner table, Encyclopedia helps him solve some of the most baffling crimes. With ten confounding mysteries in each book, not only does Encyclopedia have a chance to solve them, but readers are given all the clues as well and can chime in with their own solutions. Interactive and funits classic Encyclopedia Brown!
Sally Grindley
"Strange piles of earth keep appearing on the village green. Where do they come from? The bear Detectives must investigate!"--Back cover.