A necklace bomb exploded killing a man and a good friend of Horatio's. With his friend gone, Horatio works double the strength into this case, which worries Megan, who lost her husband in the line of duty. With two more bombs, they are put to the test to find out who is doing it and who are the targets. With evidence in hand, they search a Colombian port and discover things about the workers, that they think will help the case. But, after they find that out, the CSI team discovers the bomber is after the bomb squad.