Magnus and Tesla investigate a former Praxian stronghold and unintentionally stumble on vampiric secrets.
President Martinez makes a triumphant albeit shaky return to the White House, determined to punish the traitors who conspired against him. Sophia forges ahead with her plan, while battling a new enemy -- the guilt that has begun to plague her. Sean and Vicky form an impromptu team with Sterling and Simon in order to track down Sophia's headquarters and stop her before the destruction of all human life.
A new alter comes to light that put Charmaine's new baby at risk. Soon later, Alice visits Dr. Hattaras and intrigues him in Tara's case again. Kate, Max and Marshall fly to New York where they get to meet Kate's new friend Evan and his son.
With his th birthday rapidly approaching, RJ asks his dad for driving lessons. He gets way more than he bargained for when Rick takes him to Hunkeez, a male strip club.
Kelly Parker's manager, Shelia, arrives at the gym and starts scheming to make Kelly the most recognizable girl on the team, which includes trying to get Kelly to sabotage Kaylie by exposing her anorexia to the public. Meanwhile, Payson and Max come across a stray puppy while out jogging, and as they try to keep the puppy hidden until they can find it a home, Lauren becomes jealous of the amount of time they're spending together.
The case against Alderman Gibbons escalates when Colvin, Wysocki and Evers scramble to locate a star witness. Meanwhile, as Liam rushes to collect more evidence, he is forced to take matters into his own hands.
As Senior makes an offer that he claims Junior rejected — and Junior claims Senior took off the table — both parties wonder whether the other really wants to move forward. PJD starts their charity-bike build for CrankyApe, one of two they are building for the company, while at OCC, the crew is underway with a triple bike build for Trans Am Depot. Then, Senior's dog dies and Junior reaches out to his father.
Rob jumps into the ring at a Wrestlemania event when the WWE teams up with the Make-A-Wish Foundation in Atlanta, Georgia. With the help of Drama, Big Black, and wrestling legend and hall of famer Rowdy Roddy Piper, Rob creates an unforgettable alter ego as Kid Lightning. Rob wants to make his Kid Lightning debut a special moment for the kids and develops a grand entrance. Rowdy Roddy Piper and Rob deliver a memorable performance as he flies into the ring on a skateboard and gives his Make A Wish Foundation fans an unforgettable experience.
When the hotel safe is robbed during an extravagant Indian wedding celebration, the distraught couple asks Balagan to help recover their stolen gifts- but is it an inside job or the work of professionals
Mike feels pressured when Peggy's new boyfriend asks whether he and Molly hear wedding bells in their future.
The entire town is in an uproar over Adrian's impending baby shower.
Kate's ex-boyfriend reveals some shocking information that could put her relationship with Ben in jeopardy, and Connie and Larry's fake date takes a very real turn.
When a crazed gunman open fires during a rally with State Senator Celeste Kelman, seven innocent people are killed including the Senator. With the help of modern technology, the detectives identify a solid lead and possible motive for the shooting. At the DDA's office, tensions are running high when Dekker and Rubirosa disagree on how to handle the case. Meanwhile, TJ gets himself into a sticky situation as he continues his quest to find his dead partner's killer.
With graduation approaching, Naomi makes a decision that might prevent her from graduating with the rest of her class. Liam tells Annie that he doesn't plan on going to college, and Ryan asks Debbie to move to Paris with him. An unplanned wedding springs up, but Adrianna isn't invited after the group discovers her scheme to get revenge on Silver.
Jackie visits Bill at his diner only to find that he has no pills for her. While helping Akalitus, Thor helps her face a deeper fear. Two drunk high school girls arrive in the ER after one of them face plants on the sidewalk. Coop is attempting to throw away his childish things that have cluttered his office. Jackie needs to get to Immaculate Virgin to see Grace perform in the Saint Pageant.
Robin and Barney bond when they intervene in Ted's relationship, and Marshall and Lily watch a ticking clock as he fears that he soon will be the victim of food poisoning.
When House discovers that the experimental drug he's been using causes fatal tumors, he decides to attempt to excise them himself. However, he can't complete the surgery and ends up needing Cuddy's help. Meanwhile, Thirteen's friend from prison Amy Landecker, a relapsed drug user, arrives at her apartment needing medical care after being stabbed. With her friend unwilling to go to the hospital, Thirteen enlists Chase's assistance when the friend loses sensation and movement in her arm. Also, Taub receives some unexpected news that could change his life.
Before he can kiss the bride, Chuck must enlist his wedding party to take down Vivian Volkoff and stop her from destroying the big day. When he turns to Alexei Volkoff for help, the CIA sends its toughest agent, Clyde Decker, to stop them.
Season four wraps up with an explosive finale, including the return of Georgina Sparks and Constance Billard mean girls Kati and Is, a cameo by "Gossip Girl" author Cecily von Ziegesar, a performance by Airborne Toxic Event and, oh yeah, a few very juicy cliffhangers.