The following is taken from a website. In the context below why the second part, "had signed", is in past perfect?
... The case was scheduled to be tried before the justice of the peace in the back room of the general store. The attorney for the railroad immediately cornered the rancher and tried to get him to settle out of court. The lawyer did his best selling job, and finally the rancher agreed to take half of what he was asking.
After the rancher had signed the release and took the check, the young lawyer couldn't resist gloating a little over his success, telling the rancher, "You know, I hate to tell you this, old man, but I put one over on you in there..."