“Grey’s Anatomy” left fans with a major cliffhanger last week with the conclusion of episode 15: Did Derek (Patrick Dempsey) really cheat on Meredith? That stomach-turning question was then explored in tonight’s installment of the hit ABC series titled “Don’t Dream It’s Over.” But if you were holding your breath for an answer by the time episode 16 ended, you may want to take a deep exhale now because spoiler alert -- it didn’t happen.

But don’t worry! Shonda Rhimes, creator of the medical drama, didn’t leave us completely empty handed. Although Derek’s alleged infidelity still remains a mystery, fans were given a taste of what the bittersweet truth is. In tonight’s episode, Derek returned home for the first time since he started his new gig in D.C. “I took the first flight. Left my keys,” he told his wife after struggling to get the front door open. Did Derek come home out of guilt? Or is there an innocent reason behind his arrival and the reason why a woman with a perky-sounding voice answered his phone?

Maggie (Kelly McCreary), who was suffering a concussion after getting clocked in the head by an unruly patient, had the sense to ask the same question. As Meredith debated her husband’s loyalty amongst friends, Maggie suggested that perhaps the reason he didn’t answer his phone was because Derek was in surgery and a nurse picked up along with a few other circumstances.

Meredith, however, wasn’t convinced that Derek was guiltless considering he’s no stranger to adultery. (Derek cheated on his former wife with Meredith.) “What if he’s doing the same thing now?” Mer wondered if history was repeating itself.

Another note-worthy occurrence from episode 16 stemmed from the medical drama of the day. In tonight’s installment a man who appeared drunk (the same guy who punched Maggie) injured an expecting couple during a car accident. As it turned out, the elderly man was not intoxicated but had a version of Alzheimer's, which was cured due to the collision. After becoming lucid and learning the soon-to-be mother had died from the crash, the patient opted to not have the surgery that would prevent his memory from fading. He wanted to forget what he had done. Because he was in the right state of mind when he made the decision to forgo the operation, the doctors had to honor his wishes.

His admittance to the hospital then opened up the conversation about Alzheimer’s. In episode 16, Richard (James Pickens Jr.) confessed to Maggie that in addition to his wife dying of the disease, Ellis Grey, Maggie’s birth mother, had also succumb to the illness. “Oh my God,” Maggie responded, nearly fainting. But Maggie wasn't shocked that her mother had Alzhemiers, she was more surprised -- and thankful -- that her birth father was free of the disease. Maggie then admitted to carrying the gene. According to the doctor, she learned of her fate when she was very young.

Other major moments from episode 16:

  • After catching Callie (Sarah Ramirez) locking lips with a blond, Arizona warned her smitten ex that the woman she’s seeing was someone she used to date but ended up leaving due to her crazy behavior. (Think matching tattoos for their four-week anniversary.)
  • Following the tragedy of their son’s death, Jackson (Jesse Williams) and April (Sarah Drew) strove for normality. After arguing how regularity would be achieved, the couple ended up in the back seat of a car.

What did you think of episode 16 of “Grey’s Anatomy”? Sound off in the comments section below with your thoughts.