The team tackles a strange case, involving a suspect who impregnates young women before killing them.
When the gang help Barney's mother move, they learn that she has lied to him about events throughout his life; Robin oversells Ted to a blind date.
Barney tries to make his life seem more exciting as he bonds with his father; Robin encounters a guy she likes.
The gang recognises similarities between their significant other and their parents; a string of unfortunate events ruin Nora and Barney's evening of romance.
The hospital is locked down when a newborn disappears from the nursery; new insights about the team's personal lives, relationships and regrets surface.