The Doyles show their sentimental side as they help Jake’s high school girlfriend run off into the sunset with her new husband, who’s running from both bad guys and good guys to just get away; Rose’s past comes back to haunt her in the form of her ex-con husband, while Leslie weighs whether or not she wants Jake in her future.
A grieving widow hires the Doyles to find out why her husband left a generous sum of money in his will to a woman she’s never heard of. Rose continues to battle with Martin over their divorce while Mal formulates a plan to get Poole out of their lives for good; and Leslie and Jake hit a comfortable stride as friends and colleagues - just as his divorce from Nikki becomes final.
When a dubious chip truck owner notices his truck is missing - along with his driver/best buddy - he cons Jake into taking the case; Martin really crosses a line with Rose and she takes matters into her own hands; and Jake’s divorce becomes final and he’s happy to tell Leslie that he’s now a free-agent. But Leslie’s just been bumped up the ladder with a promotion to Sergeant, and her eye is on the job, not Jake Doyle.
When Mal suddenly leaves town and lends Jake out to be shadowed by a pompous crime novelist looking for inspiration, Jake’s entire life, including his constant relationship woes, is put under the authorial microscope; a simple cheating spouse domestic case turns out to be something far more devious than it first appears; and Jake, expecting the return of his father, gets an unwelcome surprise when it’s not Mal standing in the kitchen to greet him but his troubled older brother, Christian.
A new case gets Jake and Mal caught in the middle of a daylight-kidnapping gang, which they quickly discover is all just a game. The game takes a sinister turn when one of the players turns up dead, and it's up to the Doyle P.I. Agency to find the killer in a very real murder. Des practises his investigative skills by tailing Tinny and finds out some very disturbing information.
It's matrimony -- Doyle style -- as Jake and Mal are tasked with finding the person responsible for sabotaging an upcoming wedding; Mal and Rose fix a bump in the road in their relationship as Jake and Allison hit a stride in theirs; Des comes to Tinny's rescue but ends up exploding her plans in the process.
Jake and Mal are called to check into some death threats that have been made to a respected psychiatrist; an old "friend" from the past shows up and makes an interesting proposition to the Doyles; after Leslie's close call, Jake and Leslie find themselves struggling a little in their new romantic relationships.
Six months after the shooting of Des Courtney, the Doyles are at a graveyard mass when Mal's estranged brother-in-law (Angus Macfadyen) arrives in desperate need of help. It turns out his son, Rory (Martin McCann), has fled to St. John's after getting himself in trouble with some gangsters back in Dublin, and he needs the Doyles to find him before the wrong people do. But when Jake finally does track Rory down, he finds himself becoming an accomplice in Rory's armed robbery of an underground casino. Now that Rory has even more gangsters after him, Jake has to figure out what his cousin is really up to; all while Mal wrestles with his longstanding resentment of his brother-in-law, stemming from something that happened when Jake's mother passed away. Amongst the family drama, Jake goes to the police station to talk to Leslie, only to find that her desk has been cleared out. In her place: Constable Monica Hayward who has done her research on Jake and is not sure if he's trouble - Jake could say the same about her. Tinny, meanwhile, is helping to surprise Jake with a very special gift.
The worried Doyles and Leslie finally find out where Jake has been during his two month disappearance – but he’s brought some trouble back with him, including a rival for his affections. Tinny risks overstepping her professional bounds to help out her family. Des resolves to move on from Tinny. A stranger with a keen interest in Leslie comes to town.
Jake and Mal have no choice but to contend with a determined hitman when a man’s life is on the line. Tinny makes a big decision about her personal life. Leslie is put in the line of fire in Jake’s case – and is shocked to see it involves Callum Pardy. Des keep tabs on a suspicious businesswoman, Elaine Goodwin visiting the city. Jake has a proposition for Leslie – but is met with some shocking news.
A memory-addled Jake has must fill in the blanks from the night before when Sloan goes missing and her worried aunt, Patti (Serinda Swan) seeks his help. Mal and Des get tangled up with dangerous thug as Des avoids an awkward confrontation with Tinny. Jake and Leslie come to a crossroads in their relationship and finally make a decision regarding their future.
Jake is forced to team up with his old partner and Tinny’s father Kevin Crocker (Paul Gross), who’s on the run and desperate to prove his innocence from the murder case he was implicated in so many years ago. Jake must work double time to keep loose cannon Crocker in check as they uncover an elaborate conspiracy which goes higher than anyone suspected. As Leslie investigates the missing Chief Inspector Craig Smallwood (Steve Bacic), she is caught by surprise as someone close to her is ambushed. Des seeks Rose’s advice as he wrestles with telling Jake an important secret.
Original half hour version The Hidden Agenda pilot of Republic of Doyle with Peter MacNeill instead of Sean McGinley. also featuring Sabrina Grdevich.