Rex is on trial after his DNA is discovered at the scene of the murder of Donovan's former police informant, Karl Buell.
Tropes:
- Bad Boss: A month ago, Karl was working for Randy until the latter started to lean on him for names to help bring in a shipment of opium from Afghanistan, with Karl reluctantly doing so due to Randy threatening to hurt his mother if he didn’t. This led to Karl calling Trent to use the freighter he was stationed on to deliver the shipment as well as one filled with stolen knock off cell phones. Some time after, Karl tried to rat out Randy’s operation to the police, which led to Randy killing him and threatening to do the same to Trent if the latter did not find a way to make sure that the opium made it through. Trent managed to do so by switching the container doors to make the police think it was about smuggling phones, with the container filled with opium being stored somewhere in the yard and Randy not knowing where it is due to Trent not getting a chance to tell him about it, let alone meet him. Trent refuses to speak about his involvement out of fear that Randy will kill him, until he’s persuaded by Larissa to help the SJPD in order to repay everything Karl did for him and not make his death for nothing.
- Died in Your Arms Tonight: Karl ends up dying in Donovan’s arms before the latter can call an ambulance to their location, with Karl leaving him with the word "tross" before he bleeds out.
- Dying Clue: Karl is fatally shot while trying to deliver important information to Donovan at their old meeting place, leaving his former handler with the word "tross" before succumbing to his wound. The SJPD work to try and figure out what it means in order to find Karl’s killer and whatever it was he had stumbled upon. It was information regarding Randy’s secret opium shipment, with "tross" being the nickname of Karl’s friend Trent Ross, who was the only other person with knowledge of the operation.
- Earn Your Happy Ending: Karl’s murderer is caught, Randy is finally taken down for all of his crimes, and Otto finds a new owner in Joyce. Although Donovan expresses that the only thing that could have made it better would be if the arrest happened years ago, as Karl might still be alive, but congratulates the team on a job well done.
- Engineered Public Confession: After learning that Randy actually is responsible for Karl’s murder, Donovan sets up a sting to get him to confess everything by sending in Charlie with a wire impersonating Trent. Unfortunately, Randy manages to figure it out and destroys the wire… except he didn’t account for Rex wearing one as well.
- Identical Stranger: The forensics report reveals Karl to somehow have Rex’s fur on his clothing, despite Charlie insisting that neither he nor Rex had met him before. Because of this, Donovan tells them that the best move for now is to have Rex sit this one out until things are cleared up. The fur actually belongs to Rex’s twin brother Bucky, who was acting as Karl’s emotional support dog when he was doing therapy sessions with Larissa.
- Impostor-Exposing Test: In order to try and bust Randy for everything, Charlie is made to impersonate Trent since Randy never met either of them in person. However, Randy subjects Charlie to this trope in order to determine if he actually is Trent, with Charlie managing to answer all of the questions until Randy scrambles his headset’s signal by blocking him with shipping containers to make him fail the third question.
- The Informant: Karl used to be an informant working for Donovan back when the latter was on drug squad. He had trouble re-acclimating himself after his service in Afghanistan and got mixed up with drug traffickers, and has now become the episode’s victim trying to get important information to his former handler.
- It's Personal: Donovan reveals himself to have a long history with Randy Sher, a foreman-turned customs broker down at the shipping yards who the SJPD suspected to be behind a secret smuggling operation as well as a series of murders. They tried repeatedly to build a case against him but could never get anything to stick, with their informants either changing their testimonies or vanishing without a trace. In the present, Donovan now suspects Randy of being involved in Karl’s death, as Karl had recently been working for him up until that point despite Randy telling him that he has nothing to do with it. It reaches its peak when Donovan hears from Trent that Randy actually is responsible for Karl’s death, becoming determined to take him down once and for all.
- Long-Lost Relative: The investigation leads to Charlie learning about Rex’s siblings, specifically his two brothers, Otto (who is undergoing surgery and is currently without an owner) and Bucky (who works with Larissa in her therapy office and was acting as Karl’s emotional support dog up until the latter’s death).
- Make an Example of Them: Why Randy killed Karl when he heard that he was planning to rat him out for his opium shipment, serving as a warning to anyone else who might try to go against him. He also tries to do the same to Charlie and Rex if not for Donovan and the SJPD saving them.
- Meaningful Name: The word "tross" is the nickname of Karl’s army friend, Trent Ross, given to him by his unit, despite him preferring to go by his real name. While it is short for his full name, Trent mentions that it is also short for "albatross", which represents him as being unlucky due to numerous people dying around him. Karl was the only one who didn’t consider Trent to be bad luck, with the two of them forming a close friendship. Like everyone else, he’s deeply saddened by the loss of his friend.
- Outliving One's Offspring: Karl’s mother Joyce is devastated by the loss of her son, crying at how he was just turning his life around and that he died alone. Donovan comforts her with the fact that he was there with him till the end, and that they will do everything they can to find Karl’s murderer.
- The Reveal: This episode sheds light on Rex’s family, revealing that he came from a litter of seven consisting of three males and four females.
- Shell-Shocked Veteran:
- Karl used to be a soldier stationed in Afghanistan before getting involved with drug traffickers and becoming an informant for Donovan. He was seeing Larissa to help him deal with his PTSD, which was working until a month prior when he suddenly regressed due to him apparently having done something that he wanted to fix. He was referring to his involvement in smuggling Randy’s opium shipment, only for Randy to kill him when Karl tried to rat him out to the police.
- Trent Ross is a friend of Karl who also served in the military, having developed even worse PTSD due to his reputation of people around him always dying. Fortunately, Karl was there to help him out and helps the SJPD take down Randy thanks to a session with Larissa.
- There Are No Therapists: Subverted. Karl is mentioned to have been seeing a therapist to help him deal with his trauma, Larissa Slade. His death hits her pretty hard as well, as she mentions that he was just turning his life around. Donovan also brings in Larissa to try and convince Trent into helping the SJPD take down Randy to get justice for Karl so that his death isn’t in vain, with her managing to succeed.
