Patrick takes a personal interest in the case of a poisoned professor when he discovers the prime suspect is his former psychiatrist.

Michael gets medical attention from the most unlikely of places, and Charles Westmoreland returns to help uncover the true meaning of Scylla. Meanwhile, Lincoln and Sucre race to stop Gretchen before Scylla is lost forever.

Following the showdown against Arthur, Nathan and Peter find themselves pitted against one another, and Nathan makes a decision that will have an effect on the entire world. Meanwhile, Sylar holds Claire, H.R.G., Meredith and Angela hostage at Primatech; Ando, Matt and Daphne try to rescue Hiro and find their only hope may lie in Suresh.

Ted tries to keep his irresponsible sister from hooking up with Barney during her trip to New York, and Robin starts hanging out with Marshall at a bar for Minnesotans, not telling them that she’s really Canadian.

Dr. Keller’s body is taken over by a cunning thief, while Keller finds herself imprisoned with a death sentence on another planet.

Earl discovers that Joy has continued a holiday scam they started years before, and has expanded the scam to include her friends.

Chuck and Ned deal with the shocking return of someone from their past; Emerson and Olive investigate the death of a lighthouse keeper.

Michael, whose condition is deteriorating, winds up in the hands of The Company who promise Lincoln that they can save Michael’s life in exchange for a favor. Elsewhere, Gretchen and Self wind up with Scylla and a buyer.

In order to stop Arthur, Hiro and Clair team up and travel back in time to when Kaito gave Claire to H.R.G. Meanwhile, Peter and the Haitian head out to stop Arthur, but are stopped by Sylar and Suresh has a breakthrough with the formula.

Ted (to prove he’s not a milquetoast) and Barney (to impress Robin) pick a fight with a group of guys sitting in the gang’s favorite booth at MacLaren’s.