In case you missed last time's episode of Arrow, here is a recap. Remember when Oliver and Thea Queen almost got killed by Slade Wilson? Well, Thea's bitterness over her father Malcolm Merlyn's nearly getting her killed as well as his drugging her (which caused her to kill Sara Lance) drove her to get him kidnapped by the League of Assassins. Good news: Team Arrow managed to take League of Assassins leader Ra's Al Ghul's daughter Nyssa as prisoner.
Bad news: Thea started to suffer pains of guilt, and although Oliver and Diggle went to Nanda Parbat to rescue Malcolm from assassination by Ra's' army (hoping to save Thea from having to face the pain getting someone of her own family blood killed), Thea's pains got even worse, leading her to free Nyssa from her prison in the hope of the assassin executing her for killing Sara, even though it was not her fault.
As for Oliver and Diggle, they got captured by the League of Assassins and placed in captivity. Now, we look at this week's Arrow adventure, "The Offer", but be warned as spoilers are contained in this commentary.