Nancy Drew and the Drew Crew – Bess Marvin, George Fan, Ned "Nick" Nickerson, and Ace – had just returned to Horseshoe Bay for their summer break after a grueling college semester. The scent of the ocean and the small-town charm of their hometown welcomed them back, promising a peaceful respite. However, their plans for a quiet summer were shattered when a distressing news report caught their attention.

The local news anchor's voice crackled through the radio in the Drew family kitchen. "Breaking news from Los Angeles: a devastating fire broke out at the residence of Bobby Nash and Athena Grant-Nash late last night. Tragedy struck as Bobby Nash, a firefighter himself, succumbed to a heart attack after rescuing his wife, Athena, from the flames. Authorities are investigating the incident, which they suspect might not have been accidental."

Nancy's eyes widened in shock as she exchanged looks with her friends. Bess gasped, George clenched her fists, Nick's jaw tightened, and Ace's usually playful demeanor turned serious. Nancy grabbed her phone and immediately dialed Athena's number.

"Athena, it's Nancy. We're so sorry to hear about Bobby. We're coming to Los Angeles. We're here for you," Nancy said, her voice steady but filled with concern.

Athena's voice trembled as she responded, "Thank you, Nancy. I... I don't know what to do. I need your help. Please, come as soon as you can."

Within hours, the Drew Crew was on a flight to Los Angeles, their minds racing with questions and their hearts heavy with sorrow. They arrived at Station 118, where Athena had asked to meet them.

As they entered the fire station, they were greeted by the sight of weary firefighters and a somber atmosphere. Athena, her eyes red-rimmed and filled with grief, approached them. Nancy stepped forward and embraced her tightly.

"Athena, we're here. We'll figure this out together," Nancy assured her.

Athena nodded, tears streaming down her face. "Thank you, Nancy. I don't know where to start. The fire... it wasn't an accident. Bobby sensed something was wrong before it happened. But now he's gone, and I need to know who did this and why."

Ace, always the tech-savvy member of the group, asked, "Do you have any idea who might want to harm you or Bobby?"

Athena shook her head. "Bobby was well-liked at the station, and I don't have any known enemies. But Bobby was investigating something before he died. He kept it quiet, but I found some notes in his office."

George leaned in, her eyes sharp with determination. "We'll need to see those notes. Anything he was looking into might give us a lead."

Athena led them to Bobby's office in the station. The room was small but meticulously organized. On his desk, they found a leather-bound notebook filled with cryptic notes and references to various incidents and names.

Nancy flipped through the pages, her brow furrowed in concentration. "It looks like Bobby was investigating a series of arson cases. All the fires were ruled accidental, but he must have found something connecting them."

Nick pointed to a name circled multiple times in the notebook. "Look, 'Derek McAllister.' Who is he?"

Athena's eyes widened. "Derek McAllister is a property developer. He had a major dispute with the city council recently. Bobby mentioned him once, said he was bad news."