The first thing to do on the beach is to take the iron bar (2 points). You can try ringing the bell, but you won't get anywhere with that. For now, you'll want to head out into the ocean by using the boat. Before you do so, use the wax in your inventory to plug it's hole (5 points). At this point, the copy protection message will come up. See documentation symbols for more information on King's Quest V's copy protection.
Go south once screen and then east for three more screens to get to Harpy Island (3 points). To prevent them from eating you, use the harp (4 points). Then, take the seashell (2 points), the fishhook (2 points), and Cedric (3 points).
Now head back to the beach with the by going west three screens. Head to the house and give the old man the shell you picked up on Harpy Island (4 points). He will give you directions to Mordack's Island, so follow his mute mermaid there. Now would be a great time to save.
When you arrive at Mordack's Island (3 points), the boat will no longer be usable. Pick up the dead fish (2 points) and then head towards the gates. Take out your crystal and use it on the statues to destroy them with their own weaponry (5 points). Search the west end of the castle to find a grate. You can open this grate with the iron bar from the beach (4 points). Use the opened grate to enter the labyrinth under the castle. Before moving on, save because the labyrinth can be very confusing. Whenever you enter a new screen, the point of view is that of where you entered from. In other words, you are looking at the screen as if you are in first-person view instead of the normal frame of reference the game uses. By using look command, you can figure out which direction you are facing.
Head north one screen to find a creature named Dink. Give him the tambourine (3 points) and he'll leave behind a hairpin that you should take (2 points). Now we need to find the door leading out of the labyrinth (remember to check your direction to make sure you don't get lost). Head south one screen and then east for four screens. Now head north three screens, east one screen, north one screen, and east one more screen. Head north again two more screens and then west two screens. Finally, head north one last screen to find the door. Use the hairpin to unlock the door and enter the pantry (4 points).
Before going anywhere, grab the bag of peas from the cupboard (2 points). Save your game here! In the next room over, the kitchen, you'll encounter Princess Cassima. Give her the locket you picked up in the roc's nest (4 points). Enter the next screen and get caught by the blue creature (2 points). You'll be thrown into a dungeon where you can find a piece of cheese in a mouse hole in the wall. To take it, use the fish hook (4 points). As thanks for returning her locket, Cassima will release you from the dungeon. Now if you get caught again, you will be killed. Head back to where the blue creature caught you and use the bag of peas on him. He'll slip and fall and be knocked out (3 points). Now explore and you'll find the cat. Use the dead fish on the cat and while he is distracted use the empty pea bag to trap him (2 points).
Now head upstairs. Go left one screen to the bedroom and then down one screen to the library. Stay away from the doorway so that Mordack does not see you! Examine the book on the table to learn some spells (3 points). When Mordack enters his bedroom, enter his room and steal his wand from his nightstand (3 points). Then head to the right two screens to find a machine. Place Crispin's and Mordack's wands onto the empty trays (4 points each). To turn it on, you'll need to use the cheese on the machine to get it to turn on (5 points).
Mordack will hear the machine start up and will come rushing in. Grab Crispin's wand and be ready to fight (4 points)! Mordack will get the first shot, but thankfully you saved Cedric at Harpy Island. Cedric will sacrifice himself to protect you, giving you a chance to retaliate. As Mordack uses his spells, you must counter with one of your own. First, Mordack will turn into a flying beast. To counter, use the tiger spell (4 points). Mordack will then transform into a dragon, so use your rabbit spell to evade his attacks (4 points). Naturally, Mordack picks a snake form to eat you so you'll need to become a mongoose (4 points). Finally, Mordack turns himself into a ring of fire and surrounds. Put the fire out by conjuring a rainstorm (4 points).
Congratulations! You have just defeated Mordack and saved your family. You should have 230 points!