Mystery on Nine-Mile Marsh by Mary C. Jane, 1967.

Lucille Pierce has been feeling lonely because her other friends joined a club with some other girls that meets over the weekend, and Lucille hasn’t been invited to join. The only people who are available to hang out with now are her brother Brent and his friend Kevin, and they don’t always want a girl hanging out with them.

When Brent and Kevin have an argument because Kevin laughed at Brent’s horrible spelling during a spelling bee (Brent is horrible at spelling because he never stops to think about what he’s doing, and he gets into fights fast because he also has a quick temper), Kevin invites Lucille to join him as he goes out to have a look at the old house on Moody Island before the new owners take over. The old farmhouse stands on an island in the marsh. Sometimes, people hear odd sounds coming from the house, and some people believe that it’s haunted by the ghost of John Moody, who was lost at sea years ago. Old Mrs. Moody, John’s widow, was a hermit in her final years, and now, the only living member of the Moody family is Clyde Moody, John’s nephew. Everyone had expected that Clyde would inherit the old Moody house, but instead, Mrs. Moody left it to a man named Arnold Lindsay, an apparent stranger. Miss Rand, who owns the diner not far from the Moody house thinks that Mrs. Moody should have left it to Clyde. Clyde has had problems with alcohol and hasn’t been able to hold any job for very long, and Miss Rand thinks that having the house to care for might have been good for him, providing him with some stability. No one even has a clue who Arnold Lindsay is.

Lucille and Brent take a bike ride out to the island, but a noise in the barn frightens them away. It isn’t that they really think there’s a ghost, but they’re concerned that someone may be trespassing on the property. They decide to keep an eye on the house to see if they can see anyone sneaking around, but they don’t.

A short time later, Lucille, Brent, and Kevin meet Arnold Lindsay, who turns out to be a nice man. Like the children, he becomes concerned about the condition of Pedro, the donkey that the Turner family owns and leaves neglected in one of their fields. To give the donkey a better life, Mr. Lindsay buys Pedro, telling the kids that they can come out to the Moody house and visit him.

Mr. Lindsay doesn’t have any idea why Mrs. Moody left him the house, either. He’s a writer, but not a famous one. He just writes newspaper columns. All he or the children can think of is that Mrs. Moody must have been a fan of his columns. She didn’t get out, but she did read newspapers.

Mr. Linsday has also heard strange noises around the Moody house, and he asks the children what they know about it. They tell him the ghost stories about the Moody place, but they say that they don’t really believe that there’s a ghost. Mr. Lindsay is fascinated by the stories. He says that his impression was that the noises he heard came from the cellar, but he didn’t see anything when he investigated. He invites the children to help him investigate further sometime.

Meanwhile, Lucille tries to make friends with a new girl at school, Barbara Rosen. At first, Barbara doesn’t want to be friends because she thinks that Lucille is part of the Saturday Club with the other stuck-up girls, but she becomes friendlier when Lucille tells her that she’s not with them. Barbara had worried that the snobby girls didn’t like her because they thought something was wrong with her, but she really likes Lucille and thought for sure that she would have been asked to join the club, too, having been involved in a lot of other activities at school. Both girls find it reassuring that the fact that they weren’t asked to join the club doesn’t mean that that there’s anything wrong with them, but maybe with the girls running the club and their priorities in choosing friends. Having each other for friends makes them both feel less lonely, so they can stop worrying about the club and its members so much.

Barbara’s father owns a clothing store in town, and she says that some of his customers have been saying bad things about Mr. Lindsay. Some of them have even said that he might be a spy. Lucille thinks that’s ridiculous and that they’re only saying things because they wanted to buy the property or see it go to Clyde. Lucille has to admit that she doesn’t know much about Mr. Lindsay, so she can’t swear that the rumors aren’t true, but she still thinks that he’s probably just a nice guy, and she wants to see him keep the house so that Pedro will have a safe place to live.

With Clyde Moody and others sneaking around the property, seeming to look for something, and Clyde’s new accusations that Mrs. Moody was never legally married to his uncle and therefore had no right to will the property to anyone, Lucille, her brother, and their friends try to help prove that Mrs. Moody was really Mrs. Moody and that the house does rightfully belong to Mr. Lindsay.

Part of the theme of this story is about loyalty.  Lucille feels hurt that the girls she had previously thought were her friends abandoned her to join the Saturday Club.  She thinks that people who are real friends should stand by each other, no matter what other friends come into their lives.  However, looking back on her friendship with these other girls, she comes to realize that she was mostly friends with them because they were the girls who lived nearby, and neither of them really had other options.  In the end, they didn’t really have much in common, and she realizes that she doesn’t think very highly of them, so she is as free to move on and make new friends as they are.

Similarly, that is how some of the people in town feel about Clyde Moody.  It isn’t so much that they like him as he’s always been there.  He’s familiar to them, and it would have made sense for Mrs. Moody to will the Moody house to him.  It doesn’t make sense to them that she would leave her house to someone she’s never met, so they get upset about it and assume that there must be something wrong with the situation or with Mr. Lindsay himself.  However, nothing is wrong with Mr. Lindsay, and Clyde isn’t really worth their loyalty.  He’s a known troublemaker who associates with other troublemakers, like the Turners. Mr. Lindsay really is a better person.

In part of the story, the children catch Miss Rand sneaking around the property.  At first, they think that she was there to help Clyde or get Mr. Lindsay in trouble, but she tells Mr. Lindsay that she was actually there for very different reasons.  There was something on the property that she wanted to protect.  She wasn’t sure that she could trust Mr. Lindsay, and she knew that she couldn’t trust Clyde, so she was taking it on herself to look after it.