Sam and Annabel are on vacation with Annabel's parents in Italy. While visiting the small hilltop town of Civita, they hear rumors of looted gold from World War II buried somewhere in the town's network of underground tunnels and caves. Once again the two friends cross paths with their old nemesis, Humphrey Battleford, but he is not the only one in pursuit of the gold. An intimidating man named Kurt, the grandson of a ruthless Nazi, is also snooping around. After Annabel is kidnapped, Sam must solve the mystery of the hidden treasure to save his friend. This is the fourth mystery featuring Sam and Annabel, after Stolen, Bones and Lost.
Thirteen-year-old Chris and his family are setting up a bungee jump in his backyard. It's a real large-scale bungee jump off a bridge that connects his backyard to a small island owned by his family. Not only is it going to be the coolest attraction around, but it also provides Chris with an opportunity to watch a real engineer in action. Chris would be excited about it if things didn't keep going wrong. The rumors of hauntings on the island, once the site of a hospital for children with leprosy, are getting out of control. And there are mysterious mishaps on the bridge. Chris worries that all of these problems will keep customers away. And if the bungee jump isn't a success, his family will lose everything.
Medusa's Scream is a thrill-ride that hurtles a train through an out-of-service gold mine in the Fraser Valley. Chase can't believe his luck when he lands a summer job in the food truck outside the ride's entrance. But then he notices strange things happening at the old mine. Chase starts to piece things together, and soon his life is threatened by a villain even scarier than the snake-headed Medusa of myth.
Dylan O'Connor is in trouble again. While riding his bike home after dark, he has a run-in with a truck but doesn't give it a second thought until police show up at his door the next day. CCTV cameras put Dylan at the scene of a crime, and when the police question him, Dylan realizes he was an inadvertent witness. But he doesn't tell them the driver of the truck was Jeff Walker, a nasty piece of work. Dylan knows it's in his best interests to keep his mouth shut. Then he starts getting stalked by Jeff's weirdo sidekick, Eliot Barnes, a classmate of Dylan's. Is Eliot trying to protect Dylan, or is he making sure he stays silent?
Dan is not sure he'll survive the boring field trip to a remote heritage farm. How could a place with no running water, telephone or electricity be anything but dull? The farmer knows nothing about farming and is angry about having to conduct the tour. And what's with his tattoo? The teacher requests a private word with the farmer and then mysteriously disappears. After a messy attack of allergies, Dan is excused to find a tissue. He sneaks back to the school bus and discovers the driver and teacher have been bound and gagged. The farmer is really an escaped convict with nasty plans. Will Dan be able to find help in time?
Jim, Mickey and Lisa belong to a secret club called the Sewer Rats. Every Saturday the Sewer Rats reign supreme in paintball wars held in the city's storm drain system. The new kid, Carter, wants to join, but Lisa doesn't want him in the club. When Carter is hurt in his first paintball war, Jim and Mickey suspect that Lisa planned the accident. They try to confront her, but she runs into the tunnels just as a rainstorm begins. Jim and Mickey have to get Lisa out before the tunnels fill with water.
Left alone for the first time on the island he calls home, Simon is looking forward to a day of personal indulgence. His sister Ellen only wants to make sure they get their chores done. Their parents are busy trying to convince the government not to close the lighthouse that the family operates, and it's up to the kids to make sure everything runs smoothly. Neither Simon nor Ellen is prepared for the mysterious and potentially dangerous visitor who brings with him an unexpected storm and a riddle that may lead to treasure - treasure that could help them save the lighthouse. Simon and Ellen have to work together to solve the riddle before the stranger or the weather destroys their chances.