By Melissa Girimonte

This review may contain spoilers.

A leisurely day at sea with the family is cut short when Dexter gets called into work. He arrives at a crime scene in Alligator Alley to find a scene out of a chain email -- a human arm has been found in the stomach of a gator. The trail leads them to a photographer, Jonathan Farrow, a playboy with a taste for pretty women and a disturbing portfolio.

Dexter is still trying to get closer to Trinity, and posing as Kyle once again, ends up volunteering to help Arthur out with a project. The next morning, they head into the woods to chop down a tree. Arthur is acting quite strangely. There's a sense of inadequacy when he's unable to start the chainsaw, and Dexter handles it like a pro. On their way out of the woods, a deer jumps out in front of the vehicle and is hit. It's quickly revealed that Arthur is not capable of ending the animal's life, but Dexter's able to do it without hesitation. Dexter could have just as easily ended Arthur's life in that moment, but decides that he still has a lot to learn from this master.

Dexter does get some family advice from Arthur on finding ways to keep his children occupied so he doesn't have to devote as much time to them. Rita is pleased with Dexter taking more initiative as a parent, trying to find some activities for Cody and Astor. She credits therapy for helping them out.

Deb is continuing Lundy's investigation into The Trinity Killer, and gets Laguerta's blessing to open an investigation based on the bludgeoning death. So there's another Morgan that wants to see Trinity pay for his sins. In her other investigation, she confirms that her father was sleeping with a CI. Actually, he'd slept with more than one, according to one of the ladies Deb has tracked down.

In between everything else going on, we see snippets of Arthur working carefully with the wood from the tree that he and Dexter chopped down. The final result? A coffin. But who is going to end up in the coffin?

Despite being the weakest episode this season, there was a significant development. Dexter kills the wrong person. He was certain that Farrow was behind the killings of several of his models. It wasn't Farrow, it was his assistant, which Dexter didn't discover until after he'd murdered and disposed of Farrow.

What happens now that Dexter has taken an innocent life?

What Worked

In a season where Dexter's life is becoming increasingly more complicated, having him take the life of an innocent man opens up so many possibilities. He's always justified his actions by only killing those that had gotten away with murder. He's barely keeping up a delicate balancing act, and this move could be his downfall.

What Didnt Work

There wasn't enough focus on Trinity. He's completed his current cycle of kills, but spending an entire episode on him building a coffin seemed like a waste. Oh, and I still don't care about Deb looking into Harry's sordid past. At this point, I don't know if there's any way they could redeem that storyline for me.

Giving Credit Where Credit is Due

Dexter stars Michael C. Hall, Julie Benz, Jennifer Carpenter, Lauren Vélez, David Zayas, James Remar and John Lithgow. Slack Tide was written by Scott Buck, and directed by Tim Hunter. Dexter airs Sundays at 9 p.m. ET on Showtime.