Search and Destroy (Far Harbor)

Search and Destroy is a quest in the Fallout 4 add-on Far Harbor.

Quick walkthrough
The Brotherhood, after some time, has decided to deal with Acadia, they have sent Knight-Captain Larsen with a small team to help wipe out DiMA's community.

Detailed walkthrough
This quest doesn't really offer any advantages, and results in the deaths of everyone at Acadia.

After speaking with DiMA at Acadia one has the option to beginning this quest by traveling to the Prydwen in the Commonwealth and speaking with Lancer Captain Kells. Kells says that the Brotherhood, after some time, has decided to deal with Acadia, and they have sent Knight-Captain Larsen with a small team of soldiers to help wipe out DiMA's community.

Return to Acadia and watch Larsen and his team wipe out the synths (or lend a hand killing synths).

If having not yet completed the main Far Harbor quest line, one will now be unable to do so, and there will be no peace between the residents of Far Harbor and the Children of Atom.