Hydra has been exploiting some remarkably effective brainwashing techniques, which are able to completely strip an individual's memories of anything remotely cheerful, leaving only an angry and violent individual behind. Pierce has been subjected to this treatment, and it's up to S.H.I.E.L.D. to reawaken the man inside and heal the wounded before getting back to their lives. When it's all said and done, those lives have been changed in ways that even they don't realize.
