The Shadow Rider's Freedom Quest

Prologue
Once upon a time, a dark ship's sails appeared as a dot on the horizon.  As it came closer, one could make out the gleaming gold-painted trim that bedecked its hull and bow.  Waving from the top of the mainmast was the daunting red flag of pirates, the flag of the Marcaigh.
Slowly the ship sailed up to the beach and docked on shore. The hull made a soft sound as it slid onto the beach sand.  At that moment, a dark figure appeared on the tip of the golden bow. It was the captain.
The tall pirate was dressed in dark attire, adorned with steel gauntlets and a chest plate that gleamed blindingly as the sun appeared from behind a cloud.  It illuminated a face with a scar down the cheek and another on the eyebrow.  A closer look at the face would show that this was no ordinary pirate.  What would be expected to see a face with a mangled and rugged beard had none. There wasn't a rough speck.  A rare jewel of the sea, this pirate was female. She pulled her hand from the pocket of her slops, clutched in her fingers was a letter. It was sealed with the traditional wax seal, and a symbol that the meaning of which was a mystery to her.
The letter had been given to her the day before by a man that suddenly ran up to her; he had something important to say.  He tapped her on the shoulder.
"Are you the Shadow Rider?"
She looked suspiciously at the man He was wearing clothes of a poor man, but from what she could see in the tears of his shirt, he was very muscular, not typical of a man that used all of his strength to beg for a crust of bread or a lousy pence coin.
"I am…" She replied reticently. It was dangerous to admit to anyone that she was a wanted pirate and a key target for the British Navy.
Her eyes became wide with fear when he pulled her behind a corner, but the man did not mean harm. Instead, he passed her the letter.
"Take this.  You are needed at the place listed in the letter as soon as possible tomorrow," he whispered.
Shadow nodded as she stuffed the letter into her pocket and casually walked away.  What could this letter mean? Who needed to see her? Was it a trap? She would have to find out that day.
She slid down the rope onto the ground, landing firmly onto her feet.  She pulled the letter again from her pocket and gently tore it open to read it.  Written on the paper was a simple drawing that looked like a map and some writing in the Irish language. She had to look it over a few times to fully understand it.
"Tá sé práinneach a thagann tú anseo chomh luath agus is féidir. Tá cruinniú tábhachtach a bheidh ar siúl, agus ba mhaith linn fíorbhuíoch do láthair."
It is urgent that you come to this location as soon as possible. An important meeting is taking place and we would greatly appreciate your presence.
Signed, An Dúshlánach.