In Too Deep. The Shenanigans Series, Book Five

Three trouble-prone friends become pawns in a criminal cover-up after they discover an old bronze statue in a local pond. When Cody and Eric are denied permission to pick up golf balls from the ponds at their local golf course, they decide to trespass on the property at night. But they end up finding a lot more than just golf balls in the murky waters: they uncover a life-size bronze statue of a man! Following their discovery, the best friends start getting mysterious phone calls warning them to stay away from the golf course property, or else! But these threats only make Cody and Eric more determined to go back to steal the statue and figure out its origins.
With the help of Eric's sister, Rachel, they raise the bronze and begin unravelling clues that lead them to a long-forgotten crime. Then, just when the three think they've got it all figured out, they're kidnapped! With so many suspects in the town of Sultana, including Cody's own father, perhaps the answers to this mystery should have been left in the depths.