Find out where he bought it from and he'll tell you about
days hours remaining
If you don't want to risk your life, browse the shelves close to you for a chemistry textbook, and learn that the most common poison used in assasinations reacts with silver to turn it dull. Turn your silver bar into a silver rod. Test everything at dinner. It should be clean. Your rod will turn black as dessert is served. This means that the dish has been poisoned. Talk to the chef and he'll tell you that there was no wrongdoing. Use your Commorb on him and you'll find out that he didn't know how to cook the apple pie that was given to the Prince.
Find out where he bought it from and he'll tell you about an individual from the cooks guild who he met at the local bar. The man had expensive tastes, prefering wine to beer. You can ask for a part-time job at the bar. Use your Commorb to order wine from a customer. There will be an individual wearing illegal magic equipment. He will flee into the garden, and jump the fence. Shoot him using your ranging gear, magic doesn't affect the target. When he is almost dead the chance is that he'll be shot with an arrow which wasn't yours. The mission was accomplished, even though it was an unsolved mystery.
Mission 2: Eavesdrop on the Ceremony To start this mission, you need some Zamorak outfits. You'll need to dress in them before you are able to speak with an Chaos Druid mage (not one of the lvl 13s). He will tell you that their ritual is nearly complete however they need to get something from Lord Salarin. You can go to Sir Tiffy Cashien in Falador Park to purchase the blessed herb. The wizard will present the herb to you and the potion will explode. Mission complete.
Mission 3 - Mission 3 - This mission is sort of a sequel to Devious Minds. Remember how at the end of Devious Minds, you were told that the Temple Knights would try to duplicate the Bow Sword you made? You must now test it. You will need to have the ability to attack 20 times and have a range of 34. You will be given a bow sword and 20 mithril arrows. You will then be you will be placed in a room with some opponents. Your bow sword can allow you to inflict damage of 20 by range, and 40 when using melee. The mission is completed. You will receive additional Bow Swords as a reward. These are a great weapon to attack range and melee targets.