The Pirate King

 is the fifth and final pilot episode of the spin-off, "Backyardigans x Frontyardigans".

Summary
Captain Austin, the greatest pirate captain in the world is out on a journey to Pirate Island waiting for someone to reach the magic scepter laying on the throne inside the castle because whichever captain of the crew reaches and touches the magic scepter will become king of all pirates and rule the island forever more. What Captain Austin and his crew (First Mate Andrew, Second Mate Uniqua, Third Mate Thomas and Fourth Mate Sophie) does not know is that Austin's arch-nemesis Captain Blackmoose, with the help of his loyal crew (First Mate Pablo, Second Mate Martin, Third Mate Tasha, Fourth Mate Moe, and Fifth Mate Henwen), is also trying to reach Pirate Island and wants to be king. Along the way a crew member of one of the groups commits mutiny. Which captain will reach the magic scepter first and become king of all pirates? And which group has a traitor among them?

Captain Austin's Crew

 * Austin (Captain Austin/King Austin) - the main protagonist
 * Andrew (First Made Andrew/Prince Andrew)
 * Uniqua (Second Mate Uniqua/Princess Uniqua)
 * Thomas (Third Mate Thomas/Duke Thomas)
 * Sophie (Fourth Mate Sophie/Duchess Sophie)

Captain Blackmoose's Crew

 * Tyrone (Captain Blackmoose/Lord Blackmoose)
 * Pablo (First Mate Pablo/Count Pablo)
 * Martin (Second Mate Martin/Baron Martin)
 * Tasha (Third Mate Tasha/Lady Tasha)
 * Moe (Fourth Mate Moe/Baron Moe)
 * Henwen (Fifth Mate Henwen/Countess Henwen)

Songs

 * "I'm The Greatest Pirate Captain In The World"
 * "Race To Pirate Island"
 * "Mutiny"
 * "Hail King Austin"

Catchphrase

 * "Arrr!"