It's the Christmas season and Gibbs' father pays him a visit. Their relationship seems a bit strained.

Gibbs said at one point that he didn't believe his father would actually show up for Christmas.

They clearly have a complicated relationship but Gibbs tried, showing his dad the basement where he was building Christmas toys and asked for his dad to help him out with them.

Gibbs' father was a little off this time, though, and with a little help from Ducky, Gibbs realized something was up with his dad. Not dementia or Alzhimers, just good old-fashioned emotional distress.

It turns out someone tried to rob his store back home and, when the robber turned to attack some customers in the store, Gibbs' father killed the man.

It gives his dad new insight into the way Gibbs has spent his career. He wants to know how Gibbs does it, which is why he came.

This week's dead Marine, Tom Ellis, was murdered in the midst of his praying to Mecca out in a park.

Tom's dad is a former Marine colonel and now a minister who had serious issues with his boy becoming Muslim.

Suspect #1 is a Marine named Tibbens who served with Ellis, and harassed him about his faith in Islam. Tibbens didn't do it, but he was paid by someone unknown to make Ellis' life miserable in hopes of making him quit.

Ellis' father was paying for the abuse. He may have meant well, but this unintentionally pushed someone into kill him. But who?

His other son, Patrick, was upset at Tom's becoming Muslim and ended up killing his own brother. Tragic.