Books like Mystery of the absent neighbors by Ruth C. Wood

While attending a fancy banquet, Timothy and his cousins go out into the gardens and overhear a conversation that draws them into an unexpected mystery.

While celebrating "Christmas in July," the three cousins come into some stolen art works and discover that even bad boys can be good.

When Karen closes her eyes, the visions come. Through time and space, she sees a place where stolen children sleep. And if Karen denies a young policeman's request for help, the children may never go home again. Lois Duncan presents a ticking clock mystery with thrills at every turn.

The three cousins are stuck babysitting their bratty third-cousin Patience and when she disappears while they are visiting an old mansion, they must investigate.

*Book 1 of Ring of Evil Series* "When danger's at the controls, the final destination can be terminal. A sophisticated ring of luggage thieves has put a choke on Eddings Air, threatening to ground the young airline for good. Working undercover as baggage handlers, the Hardys agree to scope out the airline's center of operation in Atlanta. But their welcome is less than cordial -- Frank and Joe discover that they too may be headed for a crash landing! From the complex of tunnels beneath the airport to the enigmatic pasts of the airline's employees, the boys are drawn into a labyrinth of sabotage and deceit. Picking up clues to a conspiracy extending far beyond a few missing suitcases, they begin to suspect that much more than the future of Eddings Air is at stake. A scheme is in place, a plot about to unfold, in which murder is only the beginning." (Hardy Boys Encyclopedia 1993)

"Stay away from the Witch! It's a jinx boat!" Such a grim warning would surely frighten a less courageous girl than Kay Tracey. To Kay, whose skill as an amateur detective is already well known in her home town, the threat is a challenge that cannot be ignored. She must find out why someone is trying to keep her from going aboard the Witch! Defying the jinx, Kay and her friends the Worth twins, peppy Betty and studious, quiet Wilma, board the trim little houseboat for a summer trip down the Sharon River. Sailing close behind and always mooring near them, is the strange black Ajax, guarded day and night by a vicious watchdog. Two mysterious, unfriendly men are aboard, armed with guns and wary of any boat approaching them. At night, from the darkened Ajax, a flashlight winks a message in Morse code and is answered by beam from the shore. Can there be any connection between this sinister gang and the recent jewel robberies the police have been unable to solve? Kay, Wilma, and Betty find their holdiay cruise has turned into a precarious chase. The trail finally leads the girls to a dangerous spot from which there seems to be no escape...

On a voyage in the South Seas, an Englishman finds himself shipwrecked in Lilliput, a land of people only six inches high.

"It was a case guaranteed to spark a media feeding frenzy - a pretty young mother disappears without trace from her South Boston home. Her four-year-old daughter, the only witness - her handsome, secretive husband the prime suspect. But in the Jones's snug little bungalow, Detective Sergeant D.D. Warren suspects the picture of wholesome normality the couple has created. Jason and Sandra Jones seem like most hardworking couples raising a child. But under the surface things grow murkier. With the clock ticking on the life of a missing woman, the media firestorm is building and Jason Jones seems more intent on destroying evidence and isolating his daughter than on searching for his 'beloved' wife. Is the perfect husband trying to hide his guilt - or just trying to hide?"--Publisher description.