The race is on to find a new mayor. Thorne endorses Dr. Herrera; Fargo is backing Vincent; and Zoe is campaigning for Lucas. Unfortunately, Zoe's political activism leads her to abandon her science project partner, Kylie, with unexpected results.

While the candidates play politics, Thorne shows Allison a new chemical that Zane has developed. It will keep you cool under even the hottest of temperatures. Thorne professes friendship but will not tell Allison what she hopes to find in an old bunker. While Allison seeks the records that might reveal the truth, Zane and Carter develop old security camera footage and discover part of the secret.

During an all-candidates meeting at Cafe Diem, standard civic issues take a back seat to a uniquely Eurekan problem when a second sun erupts and settles above the town. Zane and Allison quickly realize that someone created the orb but who, and why?

Herrera is a suspect because of his ability to manipulate clouds but the real culprit turns out to be totally unexpected and completely non-political. The candidates, in the meantime, try to turn the 24/7 heat wave to their advantage. Zoe flogs sunscreen to potential Lucas voters while a strangely cool Vincent and Fargo offer iced drinks.

Carter, Allison and Zane enter the secret bunker to see if something within is fueling the fiery phenomenon. They find no fuel source; just a disturbing mystery and a defiant Eva Thorne.

When it becomes clear that the pseudo-sun is about to detonate, Zane and Carter see one desperate chance to destroy it but they will have to get dangerously close. To do that, they need a way to withstand the searing heat.