Trust Metric is the first episode of the fourth season. It was released on 28 September 2007.
Peter MacNicol returns as a regular cast member. Colby is being interrogated by a man named Agent Kirkland, who passes him a handcuff key and gives him escape instructions. Don and his team get information about and from Colby and must figure out if that information is reliable then realizes that everything about Colby being a double agent may not be what it seems.
Aired on Mike Johansen's, Naomi Watts's, Moon Unit Zappa's & Ed Sullivan's birthday.
At the beginning of the episode, there's a portion of the tape that Don is watching that is supposed to be a recording of a scene from the previous episode, "The Janus List" (3.24). However, the scene depicted on the tape has notable differences from the original scene.
[This appears on the beginning of the episode] 13 ships 16 miles from shore 3 drugs 2 identities