[quote=@Saffirra Dusk]
<Snipped quote by VKAllen>

What kind of mage doesn't have some kind of spell book with them? Every mage has some kind of spell book.. Some may not be the physical kind of spell book... but "EVERY" mage has a spell book... and as a rogue.. if it was the physical kind of spell book.. which it most likely is.. noting that he is level 1 and hasn't learned how to make it not physical.. Sionnie could find it and steal it.
[/quote]

A Sorcerer, A Warlock, A Druid, An Eldritch Knight, An Arcane Trickster, and a Cleric do not have spellbooks and they are the mage classes. They learn, commit and forget their spells.

[@Sionnie] I am going to have to ask you to do an Investigation Check with disadvantage in order to find his spellbook. A disadvantage means that you need to roll 2d20s and take the lower number.

EDIT #2:

If everyone could tell me first what course of action they want to do before they post, that'll be great. Saves you guys from having to edit your posts. Many courses of action will require dice rolling.