-While riding bikes with Erin and Nicky, Danny's son Sean takes a fall and suffers a head injury. He is unconscious and taken to the hospital.  The entire family rallies but there is nothing to do but wait.

-A serial sniper is shooting and killing motorist driving gas guzzling vehicles. He uses "green ammo" that has lead alternatives in it and leaves garbage from a green market in the trash near the site of the crimes.

-Danny and Kate track down Richard Leaf the head of an environmental movement. He puts them on the trail of an ex-military type he says may have committed the crime but when they track him down it appears he's committed suicide.

-Danny realizes the victim was murdered when it appears he shot himself with his right hand when he was actually left handed.  Leaf set them up. Leaf runs and in the ensuing chase he is hit by an SUV and suffers a broken leg while Danny arrests him.

-Back at the hospital, Sean finally wakes up with Danny and Frank by his side.