When you arrive back on the Normandy, you will enter the War Room sad and defeated. Speak with your squad-mates, Traynor, and Joker to formulate a plan. Traynor tracked Kai Leng’s ship as far as she could, and it led her somewhere around Horizon. Kaiden or Ashely, if present, will insist that he/she was stationed on Horizon during Mass Effect 2, and that there was virtually no Cerberus presence out that way. Still, it’s the only thing you’ve got going for you, so it’s at least worth a shot at checking out. You and your squad will decide to investigate the area for any trace of Cerberus presence, and use this information to follow Kai Leng and the Illusive Man back to their base. From here, you will strike against them and take back the prothean VI.
After this conversation, you will want to make your usual rounds of the ship. If there’s anyone you have neglected to talk to recently, you should catch up with them before making the rest of your rounds. Check your email when you are done, as you should have a few important ones since you last checked. If Tali lived and is still on your side, head down to the Engineering Deck to speak with her to further your relationship with her. Express your frustration at how the last few missions have turned out, and Tali will provide a sympathetic ear for you, getting you closer to a romance, if that’s what you so desire. Also speak with Engineer Adams and Kaiden or Ashley, who can also be found in the Engineering Deck. They will give you some information about Liara, and how hurt she has been since the mission on Thessia.
Next, head to Liara’s office and speak with her. She will admit to some guilt over the way that the last mission went. Use the Paragon option to console her just a little. This will preserve your good standing with her in a relationship. Finally, be sure to speak with Admiral Anderson in the War Room if you haven’t already. When all of that is said and done, you will be ready to investigate Horizon.