From The Perry Mason TV Show Book
In this episode Perry must defend a man with a motive. Peter Cole walks in his sleep and has been found more than once roaming the house, unaware of his actions. One night, he was even found standing over his wife's bed holding a knife. Now he's been accused of stabbing someone he mistook for his former partner (who was attempting to extort money from him). Cole hires Perry to handle his difficult defense.

Perry needs all the encouragement he can get. Thanks to Della, he gets it in the famous shoulder-rubbing scene.