What’s better than one pirate? Two, of course!

“Once Upon a Time” fans are not going to want to miss a second of Sunday’s upcoming installment. Episode 15 of Season 5 will reunite Hook (Colin O’Donoghue) with his beloved brother, a character fans have seen only in flashbacks.

The synopsis for episode 15, titled “The Brothers Jones,” teases that Hook and Emma (Jennifer Morrison) will be working together with the rest of the Storybrooke heroes to find a way to defeat Hades (Greg Germann) and return home. And surprisingly, someone from Hook’s past might have the answer they’re looking for. His brother, Liam (Bernard Curry), will reveal that there is a book that contains “the key” to taking down Hades. The catch is that the book has only been spoken of by souls who have attempted to overthrow the ruler of the Underworld. And since Hades is still wreaking havoc on the dead, it’s safe to assume that those who tried and failed.

As the group searches for the mysterious book, Henry (Jared Gilmore) will be embarking on his own secret mission. The episode description doesn’t say exactly what Henry will be up to, but fans can’t forget about the bombshell that Cruella (Victoria Smurfit) dropped on him a few weeks ago. Cruella told Henry he has the power to change all their fates and get them out of the Underworld with the Author’s pen. Henry destroyed the pen when he broke it in Storybrooke, but like every other dead magical thing, it’s now “living” in the Underworld. If Henry finds the pen, he’ll be able to rescue everyone. But, of course, that sort of power could backfire for the teen.

Elsewhere, Hades will continue playing games with the Storybrooke heroes. He’ll pit them against each other to trap them in the Underworld. And based on the trailer, it might work. Emma confesses to Regina (Lana Parrilla) that Liam doesn’t think she’s good enough for his brother. Hook will have to choose between family and the woman he loves.

Finally, viewers can expect another flashback to give more details about Liam and Hook’s close relationship.

Catch episode 15 of “Once Upon a Time” when it airs on ABC Sunday, March 27 at 8 p.m. EDT.