Sayid faces a difficult decision; Claire sends a warning to the temple inhabitants.
Blair relies on help from an unlikely source.
A leak of classified information from the CIA puts the lives of several operatives at risk, so the team works swiftly to expose the mole.
When Nicolas tells Caroline that he is going to leave his wife for her, she freaks out and drags Max into the panicked mix.
In the season premiere, Serena has gone missing.