The Executioner and the Twi'lek

Cailen Akaan is a mandalorian bounty hunter, to be more specific one of the last original Executioners. His Job is to kill the most wretched and most wicked throughout the galaxy and collect the bounty's on their heads.
As he visits Nar Shaddaa for a contract, he meets a Twi'lek mandalorian, who works for the republic intelligence service.
Days later their paths cross again.
Then he is hired by the same girl for a mission
What seemed like a simple mission at first, ends in a disaster that could cost many lives.
Will they give their own lives to save those of many others or find other way to prevent the deadly event?