Nicki is determined to solve the mystery at Pine Grove Middle School when a student's research paper is stolen and circumstantial evidence points to her new friend Kim, a Korean American.
A man's angry voice echoed in the house and reached the girls outside. "You're a foolish, silly old woman!" the man yelled. "And one of these days you'll realize how wrong you are to oppose me. Just you wait, old lady. You'll be sorry!" Nicki, Laura, Christine, Meredith, and Kim have found a new friend in Lela Greaves. But someone has threatened Ms. Greaves and now she could lose everything she loves. The girls have one clue that they hope will lead to something to save Ms. Greaves-if only they can solve the mystery before it's too late!
With a burst of nervous energy, Nicki dove to the safety of the windowless side of the shed. As the others glided into place beside her, she put her finger across her lips and knelt to listen. "It's too hot in here," a voice said. "It's too hot everywhere tonight, after your brilliant move," another voice answered. "I hope you're not planning on hiding out here until everyone calms down. You'll be here a week." Christine's brother, Tommy, is in trouble, but he doesn't seem to realize it. Nicki, Meredith, Christine, Kim, and Laura take on an investigation that pits them against a danger they've never faced before-one that could lead to a life-or-death struggle.
Nicki saw Jeremy give Meredith a puzzled look. But then there was no mistaking the snarling howl that erupted from Mr. Nichols' yard. It was just like Jeremy's nightmare. Nicki turned and saw the gate on the tall wooden fence swing open. There was a flash of bristly fir and teeth and anger. Killer was loose, and his fangs were bared and gleaming. He was streaking right toward Jeremy Newkirk! Pine Grove's track star, Jeremy Newkirk, has always been afraid of dogs, but now somebody is using that information to scare him out of Saturday's important race. Without Jeremy, Pine Grove will never win! Following a trail of mysterious letters and threatening phone calls, Nicki and her friends are in their own race against time to solve the mystery. Can the girls keep Jeremy's worst nightmare from coming true?
In the gathering darkness, Nicki and Christine swam quietly toward the Mary Celeste II . The water was as black as ink around them, and Nicki tried not to think of the living things that might be passing by her in the warm water. They reached the stern of the boat where the overhead light on deck threw shadows in the water. Nicki lifted her face mask. "Are you going to climb up, or should I?" Christine's mouth fell open and her eyes bugged. "Behind you," she squealed. "Look!"Nicki whirled around. Behind her something was rising out of the water-something big and dark and sinister, with arms like a giant sea serpent! Nicki Holland expected fun and sun in the summer before her eighth grade year-not mysterious strangers and counterfeit cash! Nicki, Meredith, Kim, Christine, and Laura are warned to leave the mystery alone. But when Nicki is threatened, she has to solve the mystery to save her own life!
"Hurry," Laura urged Meredith. "This place is spooky when it's this quiet. Meredith stood at the end of the lane, concentrating. Suddenly the few remaining lights flickered. A bright figure appeared from nowhere and seemed to float over the lanes until it hovered over lane thirteen. "Ohmigoodness," Christine whispered. "This place really is haunted!" Nicki and her friends thought it would be fun to help Meredith's uncle at Lowell Lanes for the summer. But then the lights went out and strange things began to happen. Is Lowell Lanes really haunted? Can Nicki and her friends solve the mystery before Mr. Lowell is driven out of business?
Nicki tensed when a muffled sound from the other room caught her attention. She couldn't see into the room where Krisha, Christine, and Laura were sleeping, but she could hear the faint sound of someone moving around in the darkness. Had someone come in? Had they forgotten to lock the deadbolt on their door? Nicki slipped silently off her bed and padded across the floor until she was in the doorway. She stiffened as she heard a thump from the closet. If the girls were in their beds, who was in the closet? Something jerked on the edge of her gown, and Nicki clapped her own hand across her mouth to smother her scream. Nicki and her friends thought they were taking a nice vacation trip to London, but strange things begin happening even before the girls arrive at their hotel. And when Laura's diamond birthday bracelet disappears, the search leads Nicki and her friends to more danger than they had bargained for!
A shadow fell upon the group as if a huge hand had passed before the sun. A rumble came spiraling down from the clouds overhead, and the wailing of the wind brought goosebumps to Nicki's arms. Nicki looked toward Meredith, who opened her mouth in a soundless scream and pointed to something behind Christine. Coming straight toward them was a radiant ball of dancing light. Without warning, the light ball darted into the leaves of a nearby oak tree. Even the air seemed to hold its breath until the top of the oak tree exploded in a shower of green leaves. Nicki and her friends are thrilled when they receive an invitation to spend a few days at a 500-year-old Irish castle. Shrouded in mystery and fairy legend, the castle is everything they expect, and more! The girls must battle the sea, superstition, and their own fears as they undertake a dangerous search for the legendary treasure of Cravenhill Castle.
To whom it may concern, Thank you for taking care of my baby, Rosalind. I hope you will forgive me for the unexpectedness of this situation, but I cannot give Rosalind the home she deserves. I hope you will see that she is well taken care of and loved. Please do not let anyone harm her. Tell her I loved her very much. Thank you. Nicki and her friends expected a normal flight home from Ireland until Laura meets a woman in the airport and offers to watch her baby. When the woman fails to board the plane with the girls, Laura and Nicki find a note in the baby's diaper bag. Did the mother really abandon the child? Was the woman in the airport really the baby's mother, or was she the kidnapper? Nicki and her friends have only eight hours to find answers to their many questions about the baby in their care.