Robin shows up with a date and this motivates Ted to ‘get back out there’. We also learn something major about ‘the Mother’.

Eureka’s air-conditioning system develops a fault, causing sexually tense situations, when the female residents suddenly become attracted to Carter due to bacteria.

Michael is once again imprisoned, but now in SONA (Panama), together with T-Bag, Mahone and Bellick. The prison is solely ruled by inmates, whose local prison-lord Lechero feels threatened by Scofield’s ‘fame’. Lincoln tries legal means to get Michael transferred, and gets a call from a relative. Both receive the same message, through different channels, from The Company.

Paramedics try to resuscitate Susan Farrell. They believe that she took promicin and lost the 50/50 lotto that comes with it. Danny is certain that she did not take the shot. After arriving at the hospital with the paramedics, things get complicated as everyone around Danny start to die. Garrity and another NTAC agent are sent to the hospital to assess the situation.

In the fourth-season finale, Sheila learns that Jimmy’s ghost has been spotted on several occasions, so she investigates. Meanwhile, Colleen blames Tommy for her failed relationship; Franco and Natalie come to an understanding, as do Lou, Cousin Mike and Latrina; and Tommy spends time with his father.

Zoe and her friends lose their voices, but whatever is causing the symptoms has an even worse effect on Allison and her only hope comes from an unusual source.

Meghan and Diana learn how to remove the entity from Tom, but the procedure is dangerous.

Meanwhile, Shawn finds help in his attempt to rescue Kevin from Promise City; and Jordan is betrayed by someone close.

Tommy plays hero in someone else’s uniform, confusing the crew; Colleen finds a new reason to get upset with Tommy; Natalie asks Franco for a favor; a rift between Mike and Black Shawn nearly leads to blows; and Tommy makes a move on the chief’s daughter. This does not please the chief.

Strange happenings and spreading radiation at Global Dynamics lead to speculations that an abandoned research project concerning invisibility might have been revived. When Sheriff Carter accidentally becomes involved, the effects of invisibility threaten his life.

Kyle breaks quarantine to find Jessi and they use the photo from Baylin’s lock box to search for answers. Meanwhile, the Trager’s sort through all that they know about Kyle in order to make sense of who he really is.