American Ninja 3: Blood Hunt

Sean's father was a Dojo master who was guarding the stadium during a Judo-Karate tournament. The robbers targeted the stadium specifically to loot its collections, and Sean's father was killed while trying to protect his son during the chaos. The assassin who shot him was revealed to be working for a scientist connected to General Andreas, making this seemingly random robbery actually part of a larger conspiracy.

Earlier in the film, it's established that the assassin had a distinctive wart near his left eye, which becomes a key detail for Sean's later revenge.

General Andreas ordered the assassination of Sean's father during the 1979 robbery. The shooter was one of Andreas's operatives, and the attack was not random, it was part of Andreas's early operations before he became involved in the DNA-altering terrorist plot. Sean discovers this connection when he learns that the same man who killed his father is now working for Andreas.

The DNA-altering serum is a groundbreaking genetic engineering tool developed by scientist Marjoe Gortner under Andreas's orders. It is designed to create "superhuman" candidates for terrorist operations by genetically enhancing individuals. Andreas uses the world karate championship in San Juan as a hunting ground to identify and abduct skilled fighters for his experiments.

The serum is why Andreas specifically targets martial artists like Joe Simpson and later attempts to select Sean for the program.

Chan Lee is revealed to be an operative working for Andreas, not the ally she appears to be. She masquerades as Izumo, Sean's captured mentor, to lure Sean into a trap. Her mission is to capture Sean and select him as the prime candidate for the "superhuman" experiment due to his exceptional ninja skills.

After being captured during the failed rescue attempt, Sean battles his way through the lab against Cobra and the genetically engineered ninja clones. The specifics of his escape involve using his ninja training and combat skills to fight his way out, with the final confrontation taking place against General Andreas himself.

Izumo, Sean's ninja mentor, is captured by Andreas's forces and held as bait to lure Sean into their trap. He is used by Chan Lee, who disguises herself as Izumo to deceive Sean. The summary indicates Izumo is held at the secret lab run by Cobra, though his exact fate after the rescue is not detailed in the available summary.

Despite reaching out to the authorities, Sean faces refusal from government officials to take action against Andreas and his operations. This rejection forces Sean to take matters into his own hands and devise an audacious plan to infiltrate the lab with his team, leading to the direct confrontation with Andreas's forces.

The world karate championship in San Juan serves as a cover for Andreas's dark ambitions. He uses the tournament to identify and abduct talented martial artists as candidates for his DNA-altering experiments. Sean competes and wins, drawing Andreas's attention and setting the events of the film in motion.

Sean's personal mission to avenge his father's death becomes intertwined with stopping Andreas's global terrorist plot. The DNA-altering serum has the potential to cause global chaos, making Sean's confrontation with Andreas not just about personal revenge but about preventing worldwide catastrophe. In the climax, Sean achieves vengeance while also saving the world.