"Twelve-year-old Milo is stuck spending the winter holidays in a house full of strange guests who are not what they seem--again! He will have to work with friends old and new to uncover clues in search of a mysterious map and a famous smuggler's lost haul"--

When a two-hundred-pound sea turtle goes missing from the Bayport Aquarium, Frank and Joe Hardy investigate, discovering a network of underground tunnels hidden beneath Bayport that is aiding a sinister smuggling ring.

The Hardy boys embark on another puzzling mystery when they try to discover who is stealing rare collections of ancient pirate treasure and smuggling them out of the United States.

While helping out part time in a pet shop, the Alden children discover an employee who is smuggling and selling exotic animals.

"Charlie Numbers and his gang of Whiz Kids--along with a few new allies--are on another mission: this time, to uncover the truth behind the mysterious mammoth tusk they found buried in the Boston Public Gardens. Their hunch? Blake Headstrom, eccentric billionaire, philanthropist, and collector of some renown, has been smuggling mammoth tusks into the city. The only question is: Why? Selling woolly mammoth tusks isn't illegal...but selling elephant...

When Mr. Hardy disappears while investigating a mystery surrounding a vacant house rumored to be either haunted or an abode for criminals, the Hardy Boys search for the truth.