Olivia, having been taken to William Bell's office in the parallel universe, is returned to the prime universe but with short term amnesia, unable to recall her experience there. Massive Dynamic's Nina Sharp directs her to Sam Weiss, a bowling alley manager, who gives her cryptic but helpful advice to overcome her amnesia. Meanwhile, the Fringe division has discovered several shapeshifters - a human/machine hybrid that bleed mercury - have crossed over, but unbeknownst to them, one takes the form of Olivia's partner, Charlie. When Sam's advice allows Olivia to recall what Bell told her, she unwittingly gives this information to the shapeshifter, who calls its agents to use the information to recover the body of Thomas Jerome Newton, an agent for some entity operating from the parallel universe. Nina provides Olivia with cautionary advice, alerting her to a "great war" that Bell postulated would occur between the two universes. During this time, Peter has come to forgive Walter for his past, and Walter has grown accustomed to normal life outside of the institution, but is still troubled by a secret.