Complex sentence: Frank finds out of the mix-up and attempts to stop Kevin but is too late, though with Adam's help, subdues the store clerk, Mike (Arlen Escarpeta), who is a high school friend of Adam.
Split into simpler sentences: Frank finds out of the mix-up and attempts to stop Kevin but is too late. With Adam's help, he subdues the store clerk, Mike (Arlen Escarpeta), who is a high school friend of Adam.