Someone is fishing off a boat. There are other boaters around. It looks like some kind of competition.
One of the fishermen catches something. Another one turns his boat on and leaves.
Later, we see the fisherman who left putting a fish into the bottom of his boat. Suddenly, he collapses, holding his neck. He's been hit by a dart!
Jane comes into the kitchen, starving, but Angela is on a new diet. No white sugar or white flour. Angela is full of energy, and Maura says this diet is super healthy. Rizzoli and Isles get a call and have to leave.
Jane and Maura discuss the diet on the way to the crime scene. When they get there, Frankie has lost some kind of bet to Vince about hockey. Onto the actual crime.
The victim's name is Mark Harris, and he was hit by the bolt from a crossbow. Maura says it's probably from a pistol grip. Vince says the victim was in a tournament; $500,000 was at stake. Maura finds that he was killed 3 hours ago, based on a sunburn on his face. She finds something strange about the blood pooling by his boat.
Frankie has found the victim's car. He says the victim didn't really fit in with anybody and that it doesn't make sense he would be in a fishing tournament--he's a college professor.
Another fisherman wants to talk to Jane. He doesn't know anything. He just wants to ask her out on a date.
Vince and Jane look through the trash. They find a trash bag full of fish with a note telling Harris that he was going to sleep with the fishes if he wasn't careful.
The victim's wife says Mark was a professor in Elizabethian poetry and that he fell apart after he was denied tenure. In fact, it destroyed their marriage. He got into fishing in Maine while trying to fight writer's block. He was a natural and won every tournament. She brought him divorce papers on the first day of the tournament. He ripped up the papers so he could come back home.
The wife offers the name of Linda Hendrickson, who made Mark's lures, as a suspect.
Maura has bad news. No fingerprints, the note was on standard paper, no markings on the weapon. In other words, no evidence.
Drake is his usual strange self, and Maura ignores Jane's suggestions about either getting rid of him or dating him.
Looking at the autopsy report, Maura realizes the weapon could have been shot from 60 feet away. That means more suspects.
While Nina tries to pin down a location of the shooter, Vince gives Frankie a "flour baby" that he has to take care of for one day because he lost the bet.
Vince and Jane visit Linda's trailer. She is baking something very smelly. She says Mark's death is very sad. When they first met, she thought Mark was just horny or lonely, but then realized that he was obsessed with learning about fish. She broke it off with Mark because he wasn't her kind of guy. She dated him briefly because it was hard to meet men.
Linda gives the detectives a list of all the tournament participants. She says they all hated Mark because he was the best. He was the only one who didn't cheat, and the others were sure he did.
Rizolli's admirer shows up again while she and Vince are debating whether Mark could be in love with two so different women. He asks her on a date againand gives her a bottle then goes away.
Maura found something interesting in the live fish she found with Mark. The DNA shows that fish is from a different pond and region. Jane and Maura realize either Mark was cheating or he caught someone else cheating.
Vince is annoyed because Frankie left the flour baby in the car. Saying it "died," he sentences Frankie to another day of the flour baby.
Frankie comes in holding the flour sack and tells them that there are two fishermen who have cheated in the past ready to talk to detectives. He gives the "baby" to Nina.
Vince and Frankie interview the fishermen. They both say Mark was a cheater who stole from them. Frankie's guy says that Mark stole Linda from him. Vince's guy says Mark had to be cheating and wants Vince to find out how and tell him on the down-low.
Jane's admirer shows up and asks Nina where Jane is. He notices what Nina is doing and asks about it. She gets nervous and tells him to leave. Frankie comes in and picks up his flour baby, undermining her claim that she is doing important police business.
Vince says Linda was right that everyone in the tournament cheated.
Jane and Nina talk about the case. Nina tells her that Mark Harris made a $50,000 deposit the day before the tournament started. After the tournament began, he withdrew the money. Jay Butler disappeared that day.
At the lake, Jane and Maura go boating. They are looking for evidence that the fish were taken from this lake. Jane complains about having to row manually. Maura tries to convince her to go out with Skeet, her fisherman admirer, and thinks that Jane is just afraid. Maura interrupts Jane's complaint about Skeet--they've found something. It's a trap for big bass.
Jane interviews Jay Butler, who left early. He says that he realized he couldn't win the tournament so he left. He doesn't want to be second. He explodes, saying Mark Harris was a cheater, but he doesn't know how. He says nobody can win all the time and Mark did so he must have cheated. He tells them to talk to Linda. He had to park his RV elsewhere because Mark and Linda were constantly fighting and interfering with his sleep.
Vince and Jane discuss whether Butler was telling the truth. Jane thinks he might have been.
Frankie waits for the elevator with his flour baby. Another guy waiting for the elevator says Vince forced him to get a tattoo of his face when he lost a bet and that he's not betting with him anymore. A girl who runs into the elevator also knows about betting with Vince. The elevator door closes on the flour sack.
Drake and Maura go on a motorboat and she tells him to tell Jane they rowed manually. They go to the spot where Mark caught his last fish. They throw the fish they found with Mark back into the water. Maura realizes they are in the same spot where Mark was shot. It is weird that Mark was hit in the neck instead of the back--if shot from a boat he should have been hit in the lower back. They realize the killer was standing on the shore.
Angela comes to the station with super healthy muffins. She is surprised when nobody wants them. She is vindicated when Nina tells her she looks fantastic. Angela admits she hates the diet. Nina gets a message from Vince and leaves. Angela finds Frankie's newest flour baby and picks it up.
Jane re-interviews the wife. She thinks it's funny that Mark was running a sportings good business because he hated sports. She has the money. He gave it to her as proof that he was giving up fishing and was committed to their marriage. She doesn't understand why he was killed.
Skeet comes out of the elevator and calls Jane. She asks how he keeps getting in. He offers her a dinner at Providence, a restaurant that usually has a 2 week waiting list. She tells him she doesn't want to go out with him. He doesn't understand. He is sure she is attracted to him. He tells her not to let her head rule her heart. She closes the elevator.
Maura tells Jane that the crossbow bolt was fired from the shore. Jane realizes that Mrs. Harris was very calm when talking about Mark but Linda was not. Maura says maybe Linda was still in love with him.
Jane asks Linda about Mark's prescription for blood thinners. Linda paid for them, so she must know about them. Mark won every tournament Linda officiated, but placed low in tournaments she did not officiate. They believe Linda killed Mark. She says he was hopeless, unable to catch any fish. She cheated for him without his knowledge by salting waters, sneaking fish into his bait tank and so forth so that he would be happy. But once he got the endorsement from Big Rods, she got angry because she did all the work and got no endorsements. She felt he was throwing everything away to go back to his wife. She told him how she cheated for him and he wanted to come clean instead of appreciating what she did. She felt he was ungrateful, and anyway she' d have lost everything if exposed.
Skeet shows up at Jane's office to say goodbye and to apologize for making her feel uncomfortable. He wants her to come out on his boat on a non-date. She tells him she doesn't have time. He tells her it will be only ten minutes and then she'll never see him again. They sit on his boat in the street and drink together. He shows her that he changed the name of the boat to the Janester.
Maura and Jane talk Skeet. Jane admits she's infatuated with Skeet. Vince and Frankie join them. Angela gives them regular cupcakes. She used Frankie's flour baby. She couldn't resist the flour. Vince tells Frankie he's done with the bet.