Danger Mouse (1981)

S3E1 The Invasion of Colonel 'K'

Greenback uses a shrinking device to miniaturize himself, allowing him to infiltrate Colonel K's body. His mission is to uncover the Colonel's hidden secrets and gain an advantage. As he navigates the inner workings of the Colonel's physiology, Greenback faces unexpected challenges and revelations, all while racing against time to escape before being discovered.