"Penumbra" is the 167th episode of the television series Star Trek: Deep Space Nine, the 17th episode of the seventh season. It is the first episode of the series' final 10-episode story arc. The title refers to the shadow effect of the same name.

On the station, Sisko tells Kasidy Yates of having bought land on Bajor and of his plans to build a house there.

At the bar, Ezri Dax learns that the USS Defiant has given up the search for Worf, who was lost in the Badlands while commanding a Klingon ship attacked by the Jem'Hadar. Ezri decides to take a runabout by herself to the Badlands. Benjamin Sisko from DS9 orders her to return. She unconvincingly pretends that there is too much interference to understand him. Sisko decides to allow her to look for Worf and to send her the Defiant's search log. Dax has the computer extrapolate a likely entry point for Worf's escape pod into the Badlands, then she takes the runabout in and cuts the engine, hoping that the currents will take her to Worf's position.

On the station, Sisko and Kasidy Yates discuss the plans for Sisko's house on Bajor. Sisko says he wants the house to be 'our house'. He asks her to marry him and she says yes.

On the runabout, Ezri finds Worf's escape pod after weathering some turbulence. She transports him aboard.

On Cardassia, Weyoun takes a tissue sample from the Female Changeling to give to the Vorta doctors, who have made little to no progress in finding a cure to the illness plaguing the Great Link.

On the Station, Benjamin selects his son, Jake, to be the best man at the wedding.

On the runabout, Worf is not all that grateful for being rescued. He questions Ezri's motives for rescuing him and resents her speaking as if she was Jadzia Dax. Their runabout is gunned down by the Jem'Hadar, and Dax and Worf hastily transport to a nearby planet without a comm unit.

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