Spoilers lie ahead for Episode 13 of Chicago Med Season 6, "What A Tangled Web We Weave."
Chicago Med started putting Natalie Manning through the emotional wringer earlier in Season 6 with the reveal that her mother is having very serious heart trouble, and it came down to surgery vs. Will's trial medication to prolong her life as comfortably as possible. Natalie followed Crockett's advice and Carol went the surgical route, and Natalie didn't second-guess her decision until it was too late for Carol to receive the trial meds... in any kind of approved way, anyway. Natalie stole a bottle of the trial meds, and now it seems that there may be no way for her to come back from it.
Will discovered that Kender Pharma never received the extra meds that were supposed to be sent back, and told Natalie that the pills are his responsibility, and he'd have to find out what happened to them "one way or another." This meant Will putting on the detective hat usually worn by One Chicago's other Halstead over on Chicago P.D. and trying to trace what happened, even going to security tapes.
Luckily for Natalie (for now), the footage had been automatically erased by the time Will thought to check, but it seems like only a matter of time before her theft is discovered. Even her mom was asking questions in this episode, and Will definitely noticed when Natalie scrambled to come up with a (very bad) story to explain her question about whether a dry cough is a known side effect of the drug. He had a theory that somebody grabbed them by mistake, which was probably Natalie's last chance to come clean and make it look like an accident, but she certainly didn't.
And there are a whole lot of variables in play that, if basically one things goes wrong for her, somebody finds out about what she did. Carol will have to go back to see a doctor eventually, at which point it seems likely that either she'd mention the drugs or something unprescribed would show in her bloodstream (and hopefully not disqualify her from a transplant).
Natalie's excuses are pretty thin, and the courier is a witness that she claimed that somebody else picked the meds up. Crockett has noticed that she's acting strangely, resulting in her taking steps to distance herself from him, and Will finally went and asked Natalie for the name of the trial patient she claimed to see in the ED with the dry cough. At this point, it seems to me that there's no avoiding Natalie getting caught, and what happens to her in that event really depends on who finds out first.
If her mom finally asks enough questions that Natalie has to admit where she got the drugs, Natalie is at least probably safe from being turned in. If Will finds out, things could get very complicated as he's put in a rough position. A not entirely undeserved position, but he would have to choose between protecting Natalie's career and his own standing with Kender. If he were to protect her and torpedo his future with Kender, that would at least explain how Chicago Med could keep Nick Gehlfuss around for Season 7 and beyond. Worst case scenario is probably Dr. Virani or anybody else from Kender finding out first.
For now, we can only wait and see. If I was a betting woman, my money would 100% be on Natalie getting caught, and probably by Will or her mom first. Find out with new episodes of Chicago Med on Wednesdays at 8 p.m. ET to start out the night of One Chicago action on NBC. The finales for all three shows are fast-approaching, so be sure to tune in!