Fits of violence and revenge often lead to an unending cycle. And the Oak Street Cinema understands this.

The theater will screen two of Chan-wook Park’s revenge films: “Sympathy of Mr. Vengeance” (2002) and “Oldboy” (2003) back to back – for nearly five hours of nonstop violence.

Though both feature retribution and brutality, only the more recent of the two is able to use these themes’ attention-grabbing nature to actually grab attention.

“Sympathy for Mr. Vengeance” is well-acted. And its recurring cycle of revenge and violence leaves you with an appreciation of how an act of vengeance often cannot stand alone. A kidnapping fundraiser for an organ transplant goes fatally awry and from there the violence ensues.

But the film requires a devoted viewer. The story moves slowly at times, especially in the beginning. That leaves one wondering not so much what will happen next but how as how will the next victim be tortured?

“Oldboy,” meanwhile, will keep you interested from one scene of bloodlust to the next.

“Oldboy,” too, focuses on revenge. This is true both of the protagonist Dae Su (Min-Sik Choi) and the man who imprisons him for 15 years and then releases him with no explanation. The mystery accompanying Dae-Su’s investigation into why he was singled out holds your attention until the surprise twist at the end.

Both films, however, beg the question posed most eloquently by the villain (or is he?) in “Oldboy.” What happens when one’s revenge is accomplished?

The answer is different for the two films’ myriad characters, but there is at least the suggestion that one who is consumed with revenge can rob himself of all humanity divorced from that end. When it’s over, does one’s purpose in life cease? And if so, what does that mean?

For a good exploration of that theme, check out “Oldboy” and “Sympathy for Mr. Vengeance.” If you are squeamish about torture scenes and violence, however, be prepared to look away from the screen. Several times.