Harriet tells the truth
(Book)

Even though Harriet hadn't wanted to come to Marble Island in the first place, now she doesn't want to leave. With her mom and new baby brother home from the hospital, it's almost time for Harriet to pack up and head home from Marble Island and all the friends she's made. But Harriet doesn't have time to think about that--not when she discovers that Moneypenny, her Nanu's adorable basset hound, has been poisoned. Harriet suspects the culprit is one of the guests staying at Nanu's bed-and-breakfast, and she and her best friend, Clarence, are once again on the case. But when someone else falls ill, Harriet’s going to have to sleuth harder, spy sneakier, and be willing to see that sometimes the truth is more complicated than it seems.