S04E09: 'The Shape of Things to Come'

The Black Smoke Monster makes an appearance.

Ben Linus has a secret chamber in his room.

An intruder sneaks in to Charles Widmore's bedroom in the middle of the night.

Someone close to Sayid dies.

Hurley is at the centre of a tug of war between Sawyer and Locke.

Ben tells Alex that she is not his daughter.

Bernard's special talent exposes a major lie by Daniel.