This week's episode of "The Mentalist" will be the last of the series as the hit crime procedural drama bids goodbye after running for seven full seasons. 

The two-hour double episode series finale vows to provide a bittersweet ending for the fans of the show, with Patrick Jane (Simon Baker) and Teresa Lisbon (Robin Tunney) finally walking down the aisle and starting another partnership, this time as husband and wife. 

However, things do not run as smoothly as it should as an impending danger is lurking around the corner.

In the first part of the series finale titled "Brown Shag Carpet," Jane once again agrees to act like a seasoned psychic as bait so that the FBI can zero in on a serial killer. Series creator Bruno Heller shared with TV Line that the identity of the serial killer, only known as Lazarus, is someone that viewers have not met before, but it will be as surprising nonetheless.

"And as Robin [Tunney] pointed out to me, I don't think we've done any other serial killers over the years as strongly as this one, except for Red John, so it's very much a 'full circle' kind of event," he said. 

But of course, Jane and the team succeed in finding out who the killer is. As his form of celebration, Jane pops the long awaited question to Lisbon before the end of the hour. 

In the next installment, Lisbon finally accepts Jane's marriage proposal on the final part of the episode titled "White Orchids." Yet the crime-fighting couple may not find the peace that they have long been waiting for after a vengeful killer decides to spoil the upcoming romantic event in their lives. 

The 12th and 13th episodes of "The Mentalist," which also happens to be the series finale of the police procedural mystery, will air on Wednesday, Feb. 18.