This story takes place in Year 1. Luke is not yet in a relationship with the MC.
The MC runs into Luke during work hours; Luke mentions he has to attend a banquet soon as part of a case, then leaves on an urgent matter before the MC can mention she's been invited to the same banquet by a client. He later calls her and once again has to end the call abruptly before she can tell him, so she decides to surprise him.
At the banquet, the MC looks for Luke in formal wear and is surprised by his appearance as a waiter. He subtly directs her to a quiet corner so they can talk.
The MC recalls an earlier call in which Luke had told her about the current case -- his client has been taking losses due to the investigation target taking kickbacks, and Luke is to gather evidence. The MC recognizes a guest at the banquet as someone who'd asked for suspicious legal advice at Themis, correctly guessing that guest is Luke's target and offering to help. Luke gives her an earring with a GPS and microphone and asks her to approach the target's associates.
Pretending to be the target's legal counsel, the MC approaches the associates as directed and tries to get them talking; Luke gets the evidence he needs but is stopped by security, who has noticed there are too many waiters. Thinking quickly, the MC chugs her glass of champagne and disrupts the conversation by pretending to be a drunk and unreasonable guest.
Having successfully gotten Luke away from the guard, the MC is suddenly hit by the alcohol she'd drank before her act. Luke carries her out and tries to escort her home, but he's called away for work again.
At a coffee shop a few days later, Luke chastises the MC for getting drunk in an unsafe situation as she did, then tells her to keep the earring he'd given her, as he designed it for her so she can get in touch with him if she ever needs help.