Frank and Joe are back on Black Bear Mountain, the scene of a previous wilderness adventure and mind-bending mystery. This time, the brothers are checking in on Dr. K, a friend they made during their first trip. Dr. K is a fan of living off the grid, but he’s been MIA long enough to cause worry in the small mountain town. And so the teenage detectives Black Bear Mountain relied on before have been called in to help once again.

First, a priceless painting disappears from the Bayport Historical Museum; then, two ancient samurai swords vanish from a private collection. A string of robberies has hit Bayport, and all signs point to the Phantom, a recently released ex-con who last struck more than 20 years ago. There's only one problem: The Phantom has vanished into thin air, and not even Frank and Joe Hardy can track him down.

It does not take much to convince Frank and Joe to be extras in the new zombie movie that's filming in Bayport. Not only do they get a behind-the-scenes glimpse of the magic that goes into making horror movies, but they also get to wear freakishly realistic zombie makeup that makes them look like the walking dead! But the horror gets a little too real when disaster hits the scene.

The Hardy brothers and Frank’s new girlfriend, Jones, are attending a local comic book convention on the shore. They meet up with Jones’ friend Harper, a fellow comics super fan, outside the convention. The four of them spend hours running from booth to booth and end the perfect day with pizza at Harper’s short-term rental apartment. Things don’t stay so perfect, though. On the way home, Jones realizes she switched phones with Harper by accident and she's getting some really scary texts. They show up at the apartment the next day to find it totally destroyed and Harper missing.

Rich girl Lindsay Peyton is throwing the biggest and best Sweet Sixteen bash that Bayport has ever seen. But when Frank and Joe discover that her car has been keyed, it looks like someone isn't so happy that Bayport's princess is showing off. Meanwhile, a group calling themselves the Scaredevils is filming themselves committing random mischief around town - including keying Lindsay's car - which threatens the security of Lindsay's big day.

Something is not right in Bayport. After a series of unfortunate (yet harmless) pranks, it looks like Frank and Joe have caught their suspect surprisingly early. Their classmate, Seth Diller, has taken his love of filmmaking a bit too far. But shortly after Frank and Joe confront Seth, there are fresh outbreaks of Seth-like pranks. Except these aren't as harmless. After a bit of investigating, the Hardy Boys uncover evidence of the Red Arrow - a group that will stop at nothing to bring chaos and crime to Bayport's peaceful existence.

"JOE!" Frank suddenly yelled behind me, but it was too late. A dark shape advanced on us from inside the doorway, and a bag was thrown over my head again. I could hear them doing the same to Frank too. Arms reached out and roughly pulled me inside....

A wave of motion rippled through the cattle as they broke into a run. The cows directly behind Sarah and me looked back anxiously. The entire herd would be upon us in no time. Sarah cupped a hand to her mouth. "Clear out of the way! Stampede!"

The Hardy Boys are visiting Paris! Joe is excited to check out all the street art he's heard about. And Frank can't wait to go to all the museums he's researched. On their very first day in the city, the brothers are woken up early in the morning by fireworks. But these are no ordinary fireworks. They are a part of elaborate cover for the heist of a priceless artifact.

A twig cracked. I snapped my head to the side, following the direction of the sound, and peered through the greenery. There was nothing there. As I began to turn back around, I caught the slightest motion out of the corner of my eye. Peeking out between clumps of dense vegetation, about 20 feet away, were two eyes. My skin prickled when I realized that they were staring back at me.

When Aunt Trudy wins a competition to intern with celebrity chef Colton Spark, she invites Frank and Joe to join her on her trip to the remote Rubble Island off the coast of Maine, where she’ll be helping Colton cook for the prestigious Golden Claw Awards. They’ll be staying at the island’s beautiful Seaspray Inn where the event is being hosted. Still, even before the Hardys reach the island, it becomes clear that the locals are not big fans of Colton. 

When a sinkhole opens up and swallows one of Bayport's historic statues, Frank and Joe suspect something - or someone - shady is at play. They jump at the chance to investigate: Joe as a member of an urban exploration club and Frank as a photographer for the school paper. But in the thick of their search, the boys stumble upon an entire underground city that's been abandoned for years. Now the city is home to a cultish band of criminals who plan to take over Bayport.

An original Sherlock Holmes manuscript was stolen from the Bayport Museum and now pages keep showing up in Frank and Joe's things: their lockers, menus, even the backseat of their car. It's clear someone is out to frame them. But who could it be? The boys try their usual means of deduction, but everything leads to a dead end. They just keep finding unsuspecting people who were paid to hide the pages by a mysterious third party. Frank recognizes this tactic - it's exactly what Moriarty would do to throw off Sherlock Holmes. So the brothers decide to use one of Sherlock's signature ideas.

Mr. Lakin made his way over to Don Sterling. "It's bad enough we have to suffer through your performances onstage. Now come on, we're going to be late for our own party. The whole world doesn't stop for you, you know." Mr. Lakin gave the Don's boot a kick. The Don didn't move. Joe and I exchanged glances. Something was definitely not right. Joe knelt down and put his fingers on Don Sterling's neck like we'd been taught in our first aid course.

The world's largest reef exhibit is coming to the Bayport Aquarium. Frank and Joe are stoked for the unveiling of Predator Reef, a 300,000-gallon tank that houses small sharks, rays, and thousands of colorful fish. It's also home to the aquarium's new mascot, Captain Hook - a rare and valuable, 500-pound, giant sea turtle.