Ep 3. Firecracker

In Republic of Doyle season 5 episode 3, titled "Firecracker," Jake Doyle and his father Malachy are hired by the eccentric and wealthy Augusta Winterson to find out who is targeting her with a series of threatening letters. Meanwhile, Jake's ex-girlfriend Nikki has returned to St. John's and is working as a firefighter, much to the surprise of her former colleagues. When a fire breaks out at Augusta's mansion, Jake and Nikki find themselves working together to rescue Augusta and solve the case.

As Jake and Malachy investigate the threats against Augusta, they discover that the letters are linked to a cold case from 20 years ago, involving the disappearance of a young girl. With the help of fellow private investigator Des and his computer skills, the Doyles delve deeper into the case and begin to unravel a web of secrets and lies that has been kept hidden for two decades.

Meanwhile, as Nikki adjusts to life as a firefighter, she finds herself drawn back into Jake's world when she is called to the scene of Augusta's mansion fire. Despite their unresolved feelings for each other, Jake and Nikki work together to extinguish the blaze and rescue Augusta.

As the investigation heats up, Jake and Nikki find themselves in danger as they close in on the truth behind the threats against Augusta. With the help of their friends and family, the Doyles race against time to solve the case and bring the perpetrator to justice.

Filled with action, suspense, and a touch of romance, "Firecracker" is a thrilling episode of Republic of Doyle that will leave viewers on the edge of their seats.