Plot summary
Scorpion has to outsmart the mentally-unstable Mark Collins, who has kidnapped Toby and intends to torture and kill him unless he receives Walter's BBI ( brain–brain interface ) research. But, if his demands are met, he has the ability to advance the technology to where he can read peoples' minds. When they find where Mark's hideout is through ham radio frequencies, Walter has to choose whether to capture his nemesis or let him go to disarm his elaborate booby trap—an intricate maze of dental floss holding a single jar of acid over Toby's head.
After Toby's brush with death, Walter catches up to Mark and captures him on a bus going to South Carolina, the location of his favorite childhood memory. Meanwhile, Sylvester lets Toby's marriage proposal to Happy out of the bag, but she has a marriage secret of her own. Later, Walter comes to his senses about Paige, realizing he loves her. He leaves to stop her from spending the weekend with Tim at a jazz festival in Lake Tahoe.
Credits
Adapted from Wikipedia contributors, List of Scorpion episodes. HTML formatting and reference markers removed.