Danny is home with Charlie on Christmas Eve, and Adam is preparing Danny's chimney for Santa. Adam is flying to Los Angeles to spend Christmas with Kono. Danny tells Charlie a story about a recent Five-0 case about a bad Santa who blew open an armored car. Then another Santa drives in to help the first one steal the money from the armored car. Junior drives a group of veterans to a shelter to serve Christmas dinner. McGarrett is nearby when the robbery happens and goes after the Santas, grabbing a gun from one of the armored car's guards, getting into a firefight. The Santas crash their car. They run into a Christmas parade, and get lost among all the Santas. Danny re-enacts the scene with a stuffed donkey and action figures. McGarrett catches up to one of the Santas, but has to let him go when the Santa threatens a civilian. The two Santas enter a mall. Junior and the veterans show up and offer to help. They go in and evacuate the department store where the Santas were last seen, then Five-0 moves in. All they find is the Santa costumes. Five-0 sets up a checkpoint to check IDs as people exit the mall. There is a fingerprint on a bomb part. Adam finds two bound Santas without their costumes, which meant the two bad Santas were still in costume. One gets through the checkpoint, but Junior captures him. McGarrett goes up to the roof to catch the second Santa, but the Santa gets the drop on him. Still the Santa ends up dead. Everyone gathers at the end for McGarrett's Christmas bash. McGarrett gives Junior his badge, even though he hasn't finished his coursework yet.