Twelve years after the third entry in the action franchise about unstoppable New York maverick cop John McClane (Bruce Willis), a steely computer genius (Timothy Olyphant, the series's weakest villain so far) has crippled Washington, D.C., by breaching the nation's vital data banks. McClane enlists a Jersey hacker (Justin Long, the Mac guy from the Apple ads) to reverse the damage, but the bad guys' omnipotence at nearly every turn dilutes the film's suspense. The physical stunts by Maggie Q as a lethal martial arts expert and Cyril Raffaelli as a Eurotrash sniper who rappels down buildings are more thrilling than the over-the-top chase sequences, so contrived as to verge on self-parody. Len Wiseman (Underworld) directed. PG-13, 129 min.