The adventures begin when the Happy Hollisters move into their new house in Shoreham, but the moving van carrying their toys disappears. Then they learn that their house may be haunted, with a treasure hidden somewhere inside!
A fishing contest at The Trading Post, Mr. Hollister’s sporting goods store, has everybody in Shoreham excited. After Pete catches a large fish with a mysterious tag on its tail, another adventure begins for the eager young detectives.
The Happy Hollisters are looking forward to vacationing at Sea Gull Beach with their cousins. Then they discover that the lighthouse lamp they received as a gift from Uncle Russ contains a tiny treasure, and are even more eager to get to join their relatives and search for the rest of the treasure.
Mr. Hollister plans a trip to New Mexico to purchase SW Indian trinkets to sell at The Trading Post. When family friend and Yumatan Indian Indy Roades tells them of his tribe’s lost turquoise mine, Mr. Hollister brings the whole family along to help locate the lost gems.
The Happy Hollisters are invited to stay on a ranch in New Mexico and discover a map leading to the cave of ancient dollmakers, the long-lost buried secret of the mountain. The Happy Hollisters help find the lost cave and discover a sheep rustling ring in this fast-moving story.
The Happy Hollisters head to Canada to visit their grandparents for the yearly Trappers’ Carnival and end up joining the search for a missing dog trainer and some valuable Eskimo puppies. In addition to solving the mystery, they have great fun learning to ski and drive a dog sled.
There is great activity in the Hollister household upon the arrival of Domingo, the donkey promised Sue by friends in New Mexico. The excitement mounts higher with the discovery of a note attached to the donkey’s halter signed “Y.I.F.” So begins one of the two mysteries that run through this book.
A trip to Circus Island in Florida in search of a houseboat to purchase puts the Happy Hollisters on the trail of circus dog thieves. As the young sleuths uncover sinister goings-on behind the scenes at the circus, they also learn exciting circus tricks like tumbling and tight-rope walking.
A missing letter is the key to the whereabouts of Fort Freedom, the stockade that disappeared after the Revolutionary War. The fort is located somewhere within the boundaries of Shoreham and has been sought after for many years, not only for its historic value but for the gold supposed to be hidden there by the early settlers.
Pete Hollister volunteers to locate a merry-go-round for the Lincoln School fair. Disappointments abound when a gear for the apparatus is apparently lost and a vandal sets fire to the booths and decorations in attempt to ruin the event.
The Happy Hollisters are surprised to learn that a hobbyhorse they purchased at an auction holds the key to settling an inheritance that will change the future for their new friend, Graham Stone. The mystery deepens with the appearance of a beautiful appaloosa pony, seemingly out of nowhere.
A rain storm and an unexpected guest bring new mysteries to Shoreham, along with film stars Gregory Grant and Lisa Sarno. The Happy Hollisters are invited to perform in a film about clipper ships as they search for clues.
The arrival of a crate of pineapples and an odd pet at the Hollister home leads the family on a Puerto Rican vacation. A stone found on a sightseeing tour then proves to be a clue to a pirate’s treasure. The children have fun learning new customs and a new language as they comb the island for clues.
When Mr. Hollister’s sport and toy store, The Trading Post, is robbed, his main concern is for his invention, a new type of collapsible canoe. He is therefore surprised to discover that a Geiger counter and a couple of pickaxes are the only missing items.
This story finds the Hollister family off to Alaska with Uncle Russ and their two cousins, Teddy and Jean. Russ Hollister, a commercial artist and cartoonist, has run out of ideas and is trying to think of a new location for his comic strip characters.
A visit from Gram and Gramp Hollister in the Hollister home at Shoreham opens up the opportunity for the five children to go to Canada with their grandparents to see the Mardi Gras and Winter Carnival in Quebec.
A mysterious Chinese message tucked inside a book about New York City tunnels leads the Happy Hollisters to Chinatown in search of a long-lost treasure. While Mr. Hollister works with a toy manufacturer to perfect a new invention, the rest of the family explores New York City and learns about the Chinese way of life in Manhattan.
On their first adventure outside of the Western Hemisphere, the Happy Hollisters travel to Denmark for their summer vacation. During the flight to Copenhagen, the children meet a member of the Danish royal family’s staff who is carrying a valuable reproduction of the “Little Mermaid,” the famous statue that overlooks the harbor in Copenhagen. Upon landing in Denmark, the figurine goes missing, and the sleuthing begins!
GHOST HUNTER WANTED TO RID A HAUNTED HOUSE OF SPOOKS! APPLY MRS. NEELY. THE ANTIQUE HOUSE. Their curiosity aroused over this unusual advertisement, Pete and Pam Hollister visit Mrs. Neeley to apply for the job.