When the Jeffersonian team discovers the body of a renowned but disliked chess master amidst pig slop, Sweets surprises the team with his chess skills and goes undercover in the world of professional chess to find the killer. Cam is being recognized in the "Outstanding Woman of Science" issue of a noted science publication but is hesitant to participate since she does not want to offend Brennan who knows she should be the one to be honored. Meanwhile, much to Brennan's annoyance, Dr. Douglas Filmore, the always sunny Canadian forensic podiatrist fills in as a lab intern.

When tasked with researching his school's namesake, Boyd gets a little help from Kristin and Ryan and his report causes outrage, prompting the school to reconsider its name. Also upsetting Vanessa, Mike suggests reaching out to school board member and neighbor, Carol Larabee, for help. Meanwhile, Mandy enlists Blanca's expertise for a class project.

Carrie, Mouse, Maggie, and Walt decide to go to their senior prom - at The Waldorf Astoria - together for a final hurrah. Larissa offers Carrie an opportunity that makes her rethink her plans for the next year. Mouse learns a secret about Donna LaDonna that could threaten her reign as queen bee. Meanwhile, Sebastian hides a big decision from Carrie.

Debbie struggles with going back to school and the advances of a flirtatious professor, while Marty is at home with Amber, mourning her relationship with Reggie. Meanwhile, Larry & Reggie are emotional wrecks as their Zabvronian male cycles have synchronized, and Dick is going through the "terrible tens".

Still adjusting to life back in the states, Pete tries to distance himself from his brothers and the platoon, which, of course, backfires.

Willie Louise Kellum was loved by everyone in the small, rural community of Camp Hill, AL. Every Sunday she would attend the Mt Lovely Baptist Church where she was surrounded by her many friends and her large family of daughters, nieces, nephews, grandchildren, and great-grandchildren. At 78 years old, Miss Louise had a dry wit and boundless energy as she continued to work well into her retirement as a cook at the local Head Start Program, a job she had happily worked for over 40 years. The program focuses on child development and serves many low-income families in the tri-county area. Miss Louise loved spending time with the children from all over the community; it was a genuine passion for her. The morning of February 21, 2005 started off as a fairly uneventful day. Miss Louise ran a few errands, including a stop at the local grocery store, which was the last place she was seen alive. Later that evening, her grandson who was living with her at the time, found Miss Louise lying unconscious in his room and called 911. When the Camp Hill Police arrived at her home they found Miss Louise, with a cord wrapped around her neck and bruises all over her body. Her murder rocked the entire community, as she was loved by so many. Chief Roosevelt Finley of the Camp Hill Police Department knew Miss Louise well and her murder bothers him more than any other he's investigated. He has vowed not to rest until he finds her killer.

While Hank tests Mother Nature by staying out dredging in the storm, Shawn races to bring his dredge home. Emily and Glen head far inland to river dredge. Her crew sews seeds of mutiny. Kris almost drowns from faulty equipment and Steve R's inattention.

Nick and Hank investigate a cop killer who scalps his victims. Meanwhile, Juliette begins to communicate with Nick's mom via email and Adalind finds herself much closer to delivering her baby than she previously thought. Elsewhere, Monroe's parents decide to surprise him and Rosalee with an early arrival to Portland after learning some exciting news.

When Mark Cuban hears how a Mom from Provo, UT funded her idea to design stylish baby shoes, he proclaims that hers is the best story he's heard on how to start a business. Also, a man from Salt Lake City, UT hopes the Sharks will swallow his idea for a pill that anyone can take in a situation when food is not an option; two siblings from Prairie Village, KS hope they can zip up a deal with the Sharks with their children's swimwear line that keeps kids sun safe; and an accomplished entrepreneur from San Diego, CA has a simple way to stay fit with a custom deck of playing cards that makes exercise convenient and fun. In a follow up segment, Kim Nelson from Pauline, SC gives an update on her dessert company, Daisy Cakes, which Barbara invested in during Season Two.

Legends from around the world speak of sacred entryways to the land of the gods. Gates that allowed instant passage not just beyond the confines of Earth, but beyond space and time. Are such passages - or stargates - just inventions of myth, or might this kind of interstellar travel have existed in the ancient world? In Turkey, researchers uncover a mysterious and toxic cave that the ancient Greeks described as a physical gateway to Hell. The Incas believed their empire began when divine beings stepped through portals in a mountain. In Northern Mexico, legends describe strange, otherworldly creatures appearing and disappearing within the remote ruins of an ancient civilization. As science continues its quest to create technology that would allow humans to travel to the stars, is it possible that these celestial pathways already exist?

Todd's claim owner forces a change to the mining plan. Grandpa visits Parker and makes a radical suggestion that the crew believes to be pure fantasy. Dustin fights to reach his first mountain gold.

In trying to help Barney and Maxine's budding relationship, Burt and Virginia wind up getting in a fight. Meanwhile, Jimmy and Sabrina decide to start fencing in order to relieve some of the tension in their relationship.

A public demonstration of Grayson's technology moves forward with catastrophic consequences. Lucy joins the ranks of the undead, Van Helsing exacts a terrible revenge upon Mr. Browning and Lady Jane and her huntsmen attempt to eradicate London of all vampires, culminating with a confrontation and battle-royal between her and Grayson. Finally, Mina discovers the secret of Grayson's obsessive love.

Alan and the team deal with secrets and suspicion as the crisis heightens and deadly consequences follow. Meanwhile, Walker tries to survive on Level R.

Erin Brockovich, Willie Nelson, Josh Barro, Governor Howard Dean, and Carly Fiorina.

A shocking murder near an Amish farm fractures relations between the Kinaho tribe and the Amish, who are forced to rely on Proctor to fend off a vengeful mob. Investigating the crime on Kinaho turf, Lucas and his deputies find themselves confronted by uncooperative gang members and their imposing leader, Chayton Littlestone. Meanwhile, Carrie welcomes an unexpected visitor, while Lucas deals with the sudden appearance of a most unwelcome one.

Pat McGann, Devon Avenue

Terry Bradshaw, Darius Rucker

As Twilight Sparkle eagerly anticipates the arrival of Princess Cadance, Discord dishes up quite the dreadful disruption when he arrives and begs the ponies to take care of him while he is sick. But when Discord's diva like demands get ridiculously out of hand, Twilight's generosity and friendship skills are put to the test during her special weekend.

Dr. Cockroach accidentally teleports the diner into space.

Link is disappointed when he can not play in the government football game.

The third set of hopefuls audition with the judges only able to hear their voices and not see how they look. The judges have to select ten different acts during the course of the auditions that they would each like to mentor. If more than one judge are impressed by the same act then the act has to decide which judge they would like to be mentored by.

Dixie and Rita see a woman running away from an alley in distress, and decide to approach one of the men who was with her. After one of the men hurts himself, he blames Dixie for his injuries. Ethan and Cal are puzzled by a patient who managed to lose his voice.

Jonathan is joined on the show by Sam Bailey, Robert Lindsay, Rufus Hound and Tinie Tempah.