Flint Martillo, born Genshi, is a prehistoric caveboy entombed with his father, Rocky Hammerhead, during a clash with antagonist Petra Fina while safeguarding the Time Shifter Getalong. Revived millennia later in the 25th century by Dr. Bernard Goodman, Flint inherits his father’s sentient stone axe form after Rocky’s partial resurrection—a weapon doubling as his tactical mentor. Though Flint wields raw strength and battle mastery, his strategic shortcomings compel reliance on allies Sarah and Tony Goodman for mission-critical decisions.

Tasked by the Time Police to recover Time Shifters—magical creatures dispersed across eras—he thwarts efforts by Petra Fina and the Dark Lord to corrupt these beings into weaponized "Con" entities. His struggles intensify with a metabolic vulnerability: dwindling food reserves sap his power, risking collapse mid-conflict. Over time, Flint evolves as a leader, confronting the Dark Lord’s origins and forging fragile empathy upon discovering the foe’s true identity—a desolate child exiled in timeless isolation. Their final showdown brokers a brief ceasefire with Petra before hostilities resume.

Manga iterations diverge slightly, omitting Time Police chief Jillian Gray for an older male counterpart and introducing Z•Z, a hotheaded detective pivotal to locating the Time Shifter Bubblegum. These adjustments deepen secondary plots without shifting Flint’s arc. Through every adaptation, Rocky persists as Flint’s unflinching guide, blending combat utility with fatherly counsel from his axe-bound existence.