Will is taking some much needed personal time with a fellow psychologist named Abby. He's bent the rules a little and used Helen's name to get a reservation at the city's most exclusive restaurant, Alfredo's. But on their way there, Will and Abby are kidnapped by gangsters, taken to a hideout, and told to save the life of their boss, Gibbs. Will insists that they take him back to the Sanctuary where he'll have the proper medical supplies, but the leader, a woman named Sioux, refuses. He'll save the patient now, he'll save the patient here.
Will and Abby make several failed attempts at escape, but finally Will realizes he's cornered. When Alfredo's calls the Sanctuary, outraged that Will didn't show up for his reservation, Kate, Biggie and Declan know that something's up. And when their surveillance devices show a triangulated pattern of Red List buys and a spike in thermal activity at their center, the team is able to piece together the theory that Will and Abby are being held captive, with Will trying to jerry rig an antidote to a powerful Abnormal venom. They organize an extraction team, but the mission is halted at the last minute by Helen, in absentia. She tells them that the gang holding Will has been on the Sanctuary's radar for months due to a deal they're trying to organize to sell hundreds of Abnormals into slavery. She wants to save Will, but the moral duty to stop the slave trade is stronger.
Meanwhile, Will and Abby have deduced that something's not right with Sioux - she's hiding something. Will finally concocts the antidote, but when he checks Gibbs's heart rate, he knows that something's off. Sioux had told them, in private, that Gibbs was an Abnormal and threatened Will to keep it a secret. But Gibbs's heart rate is all wrong for an Abnormal of his type. Will finally corners Sioux into telling the truth - that she knew about the slave deal and wanted to stop it by killing Gibbs. That's why she kidnapped Will, who she knew would be out of his element, and put so many restrictions on him. But all of this is overheard by one of the henchmen, who shoots Sioux where she stands and demands that Will finish his job, using Abby, who he stabbed with the poison, as leverage.
Will explains that he'll have to remake an antidote that's appropriate for an Abnormal. When Gibbs revives, he trashes all of Will's supplies, making it impossible for Will to make an antidote for Abby, and strides off to complete his slave trade. But Will thought ahead and has a syringe of human-appropriate antidote literally in his back pocket. He administers it to his sweetheart, and saves the day.
The Sanctuary team, meanwhile, has set up an ambush at the rendezvous location. They get the drop on Gibbs and his crew, and save hundreds of Abnormals from a life of slavery.