The Dying of the Light (S02E10)

The Oracle's prophecy has come true – the revelations about Pasiphae have blackened Jason's heart, and he bears little resemblance to the man we know and love. His attitude is reckless and foolhardy, and he no longer seems to care about anyone or anything – even Ariadne. Desperate to save his friend, Pythagoras sets off in search of help. But he soon discovers that not everyone is as keen to protect Jason as he is... (BBC)