6

If questioned, say you have to return a lot of library books after work.

A squashed cat is not the target of your mission. Any items that will not fit into the bag comfortably (when your cat is inside) should be either left at home or could be transferred to your purse or possibly to another bag, made to look like "all that extra work you did at home last night". However, be careful because bringing too many bags into the office may draw attention toward you - the idea is to bring one bag containing the cat for the total sneak attack.