A brand-new adventure begins as Robin, Rusty, and Rat take on a job to find a farmer’s missing pigs. Unsurprisingly, the case turns out to be a wee bit more complicated and challenging than they’d initially expected.  

With Chip now back in Jupiter Springs, the kids meet with a professor who provides valuable insights about the tree markings they’d photographed. After some preparations, the boys journey back to the place where it all began, seeking irrefutable proof of the cave creature’s existence.

[For more of the Kids on Bikes characters, also listen to SPRINGS 1-3 and Druids of Dragondale 1-4.]

With Derrick behind the wheel, Dickey and Plunger take a road trip to visit Chip in Sacramento. However, they quickly find that something’s not right with their old friend, and in fact, he might be in mortal danger. It takes their combined encyclopedic knowledge and skill mastery to deduce the situation and set things right again.

A year after their encounter at Saber-Tooth Cave, Dickey Newton and Plunger might be catching fleeting glimpses of the same horrifying entity. Dickey is skeptical, but Plunger wants to believe. Meanwhile, Chip Estrada has been convalescing in a Sacramento psychiatric facility. Can the kids uncover the truth? If so, can they handle it?

Arkham, Massachusetts. 1920s. Flapper Margo Macey has just inherited a house from her wealthy uncle who mysteriously vanished along with his adoptive daughter. She hires private investigator Saul Moran to assist her in the removal of rumored squatters. Joined by newspaper reporter Rachel Hemingway, they enter the house only to find nothing weird or bad happening there, and everything turns out fine.

The plot thickens as the kids track another clue, taking them into dark woods. There, something awaits, revealing an even deeper mystery and pushing their courage to the limit.

After their terrifying discovery underneath Hammond Bee Middle School, the kids debate the best course of action. Should they let the adults handle it? Which adults can they even trust? On the other hand, there’s an enticing clue left behind, just waiting to be followed. It leads to the Europa Roadhouse.

One autumn day in the 1980s, nerd Dickey Newton and bully Chip Estrada are at Strategy Games Club when fellow friend and conspiracy theorist Plunger tells them a rumor about an old bomb shelter underneath their middle school. They decide to test the rumor, and what they discover will change their lives forever.

Robin, Rusty, and Rat are back in the Fallen Soldier when a man approaches them and says his daughter has been kidnapped for ransom. With the “help” of the daughter’s boyfriend, the heroes begin another investigation.

While continuing to search the malodorous abandoned house, the heroes have a ghoulish and gusty experience in its bowels, ultimately leading to a confrontation with the mysterious “chap in black.”