Anna Shot, Mac Killed
That evening, Robert comes home with Anna and is a little nervous about sleeping with her in her bed. The next morning, their snuggling is interrupted by a call telling Robert the harbor's open. Certain that Mac's gonna try to leave on one of the exiting freighters, Robert, with Anna in tow, rushes off to police headquarters. Over at the Eckerts' place, Sly catches Mac coming out of the shower, but Jenny convinces her nephew to keep quiet. However, when Bill catches Mac that night, Mac knocks him out and ties Bill up.  When Bill comes to, Robert's notified but it's too late, Mac's already gone. Robert locks Anna in his office to keep her from following him to the docks, but she manages to get out, and also heads for the docks. While Robert's fending off a pack of reporters, including Tiffany, shots ring out. Nearby, someone has taken shots at Anna, who falls to the ground after trying to return gunfire. The first to arrive, Robert turns over the body and is shocked to find his lover unconscious and bleeding on her cheek.  Immediately he has flashbacks to 13 years ago when he discovered Anna was a double agent and he accidently caused her to get burned by shooting the oil barrels near her.

An armed Mac is hiding out on the docks, waiting to sneak on one of the outbound boats with Finian's help. Finian tells him about Anna's shooting and Mac realizes he'd better get out of PC quick. Certain that Mac was behind Anna's attack, Robert tracks him down and they duel it out on a ship. Before a small audience, Robert deckes Mac into the water during their hand-to-hand combat. He doesn't surface and no body is found. Robert's devastated and breaks down. Gently rebuffing Anna's attempt to comfort him, Robert instead drowns his sorrow with alcohol. He resigns as commissioner.

Finian helps a soaking Mac out of the water and hides him out in the catacombs. Delirious, Mac calls Finian "Father" and asks for  forgiveness. While Mac recovers, Finian calls Paul to tell him "It's still on." One of Mac's former shipmates, Rory, tells Robert that Mac stole his money, tipping Robert off to Mac still being alive. Rory also tells Robert that Mac is suppose to be at Chelsea Barn at Finger Lakes, then meets up with Paul, who's pleased that Robert bought the story. 

Robert shows up at Anna's and seduces her. After she falls asleep, he leaves her a note telling her he loves her and steals her gun. Anna doesn't realize he's taken off until later. Robert's suppose to show up for a hearing that morning and Frisco, Anna and Sean try to locate him before it become common knowledge. An APB is put out on Robert when the district attorney learns Robert's gone. Robin's upset when someone mentions Robert may be dead. Anna and gang realize Mac's alive and Robert's after him again. Robert's officially indicted for Mac's murder. Frisco's torn when he's promoted and put in charge of finding Robert. He vehemently defends Robert against some of his disgruntled coworkers. Bored with being a housewife, Felicia applies to the police academy and gets accepted. Frisco's furious.

He Ain't Heavy, He's My Brother
At Finger Lakes, Robert gets a love struck rookie cop named Priscilla to help him look for Mac. At a nearby clinic, a pneumonia-strucken Mac is being cared for by nurse Betty who lets him come home with her to recover. Mac later calls Jenny to let her know he's alive. Back in PC, Finian's mugged and has to call Paul for more money. Paul offers to deliver the money to Mac.

At Chelsea barn, the brothers walk towards one another, both with guns drawn.  As Robert aims at Mac, shot rings out and Robert falls to the ground. Robert, hit in the shoulder, thinks Mac did it until Mac points out he shot Rory instead of Robert. The brothers can only get the dying Rory to admit that "both of you should have been killed." Mac then carries the bleeding Robert to the clinic, where Mac donates his blood to his older brother. Since Robert's strapped down, Mac uses the opportunity to explain to his still hostile older brother what really happened after the plane crash.  He didn't desert Robert, their parents, and Robert's fiancee, Mac asserts, but instead had gone for help, and when he returned, Robert had already left, thinking Mac had deserted them all. Robert softens towards his brother, but the duo are imprisoned by the local sherrif for Rory's murder.  There, the two bond even further.  Mac confesses Paul Hornsby was his boss and his admiration for Robert's family life, while Robert confesses his distraught when he thought he'd killed Mac.  Vowing to nail Paul, the two knockout the sheriff and take off. Meanwhile, Paul arranges for a banker named Turner to take "evidence" to D.A. Schultz to discover four bank accounts registered to Mac and Robert, which forces Schultz to accuse the Scorpio brothers of criminal conspiracy. Tiff alerts Anna to the charges, and a furious Sean and Anna confront their friend Schultz. Schultz's hands are tied until the charges can be proven false.  A senator also seems to be involved with the frame up.

Finding Serenity
On a tip, Anna manages to figure out Robert took off to Finger Lakes.  Knocking out the police bodyguard, Anna hides him in the closet and instructs a surprised Robin and Olin to only tell everyone that she went after Robert. Robin refuses to say anymore to Sean and Frisco, so Sean has Robin moved into his penthouse for safety until her parents return. Arriving at Finger Lakes, Anna confronts the sheriff and his deputy, who's got a little crush on Robert, and finally tracks down Mac, who she tackles until Robert shows up and calls her off.  The two rush into each others arms, kissing, after which Anna whacks Robert in the shoulder for taking off. When she realizes he's hurt, she starts to accuse Mac until Robert explains that Mac actually saved Robert's life.  Robert brushes away a confused Anna's questions with more kisses, and Mac, feeling like a third wheel, wanders off to find shelter. 

Finding a huge, isolated estate called "Serenity" nearby, the Mac meets the mysterious Dominique Taub.  Mac's immediately in love. Dom lies to the sherrif that she's not seen the Scorpios and insists the Scorpio clan stay at her estate and that she has no phone.  The four have an enchanted evening filled with dancing and ballroom gowns. Robert insists that Anna stay in the same room with him, so the duo reaffirm their love.  Chastising Robert for not telling her where she went, he explains, "I didn't want you following me," to which she replies, "I found you anyway!"  Mac's distracted with Dom, who won't let him kiss her.  On a walk near the edges of the estate, Mac manages to rescue Dom from being hit by a rider and his horse and discovers Dom couldn't hear the horse's gallop because she's deaf.  Robert and Anna discover that Dom lied about not having a phone and Mac fills them in on Dom being deaf. "That would explain all the wood flooring," Anna deduces.