One Giant Leap... (S04E20)

With the Astraeus countdown underway, Carter (Colin Ferguson) hopes Allison (Salli Richardson-Whitfield) and Kevin (Trevor Jackson) will decide to move in with him. Personal issues get shelved when Carter and Jo (Erica Cerra) investigate a mysterious attack on the presidential convoy. Initial clues point to super-environmentalist Dr. Plotkin (Dave Foley), but when cosmic anomalies start popping up all over town, Plotkin's radical research looks like it might save the day. But not for long... At Global Dynamics, as Henry (Joe Morton) and Senator Wen (Ming-Na) oversee final launch preparations, Fargo (Neil Grayston) and Holly (Felicia Day) make some preparations of their own. Henry and Grace (Tembi Locke) exchange wistful goodbyes while Jo's farewell to Zane (Niall Matter) carries a deeper meaning he does not yet suspect. Carter and Plotkin quickly discover that their solution is only temporary and that Eureka faces certain annihilation. Their one hope is an insanely dangerous plan that puts Carter in the direct path of earth-shattering forces – but neither he nor anyone else realizes that another threat, much worse, looms over the Astraeus mission and its crew. (iTunes)