'Fringe' recap: The Past Didn't Go Anywhere
They're down a body in Fringe division, because Olivia's memory wipe means the FBI is concerned she's not the same agent they licensed. Example: she talks to an FBI shrink about how her sister went back to Chicago to be near her douchebag ex-husband. Except here, her sister is still married and she and her husband have two kids.
Of course, it's not like Olivia's going to let anything like a direct order keep her from working the case, and she shows up at the house of Marshall Bowman's partner, only to find he's a monster already; he attacks Olivia and escapes.
A tattoo of a cuneiform symbol on Bowman's corpse leads Peter to his bookseller friend, who doesn't know him or Olivia (although he can't help himself from hitting on Olivia), and with his help they track the symbol to a cult of whackjobs who are all about improving the human species; mutation by design. This is worrisome for everyone, perhaps most of all Lincoln, who may have been infected in the attack.