Mark Sheppard returns to Leverage on the summer 2011 finale. The actor portrays the character of Jim Sterling.
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This doesn't look like an ideal situation. Nate is held at gunpoint on the Leverage summer finale.
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Leverage Season 4 Episode 10 Quotes

Hardison: Because of its atomic mass, this thing is the nuclear version of "the one ring"
Sophie: Ring? What ring?
Nate: Don't get him started.

Nate: You still haven't said what's in it for me.
Sterling: I will owe you a favor. How often does that happen?