Ep 16. Ka Pohaku Kihi Pa'a (The Solid Cornerstone)

McGarrett and his team are called to investigate the murder of a wealthy businessman. The victim's son, who is suffering from PTSD after serving in Afghanistan, is the prime suspect. While the team tries to find evidence to either prove or disprove the son's guilt, they dig deeper into the family's complicated past and the victim's shady dealings. Meanwhile, Kono and Chin Ho receive a tip about an illegal arms dealer operating on the island and work to track him down. As the case progresses, tensions rise between the members of the team and secrets are revealed that could potentially tear them apart. With time running out, they must put aside their differences and work together to solve the case and bring the killer to justice.