When the kill count of a mass-murdering arsonist active in a small town reaches 31, the BAU are called in.
Ted reconnects with an old shirt and sees a parallel to his love life, beginning to think that a woman from his past is perfect for him now.
Lily gets a touch of the green eyes when Marshall goes on his first date after their split, and Marshall's date has her own ocular problem: `crazy eyes'.
Marshall gives up his dream of saving the Earth in favour of money after being courted by a lawyer from a corporate firm.
Ted's family's visit to New York leads to the discovery of a family secret; Lily and Marshall struggle to get used to their new relationship.