Marvel's Agents of SHIELD returns for its second season this Tuesday, September 23rd, with the action-packed episode, "Shadows" - which features Lucy Lawless guest starring as SHIELD field operative Isabelle "Izzy" Hartley. Agents of SHIELD: Why We're Excited for Season 2 But after everything that happened to Coulson's team, and SHIELD in general, last season, can she be trusted?