Barbara Kottmeier

When a group of wedding guests in Massachusetts suffocate from the inside out, the team must find out how the toxin was delivered and targeted.

Oliver collapses at a charity event and reveals he only has 24 hours to live. Clark and Chloe call Davis for help but his prognosis is grim. Delirious, Oliver flashes back to when he was stranded on an island and first learned how to use a bow and arrow. He also recalls meeting Tess for the first time on that island after she had been kidnapped by a drug runner. Meanwhile, Chloe decides to use her new powers to help save Oliver, shocking Clark.

Eight out of the original 25 suspects strive to be one of the few final survivors as all answers are finally unveiled in the series finale.