e.l.f. Skin Youth Boosting Advanced Retinoid Serum (£22)
Spot it: In Regina's room
Finding a decent retinol serum can be confusing, but trust me when I say that this one from e.l.f. is a good one. A really good one. Instead of retinol (the most commonly used type of retinoid and the one you've probably heard of before) it uses a mix of retinal and granactive retinoid which work much faster than retinol and are far less likely to irritate your skin. These ingredients are normally only used by more expensive, premium skincare brands (think Medik8, Skin Rocks, and Roc) making this a total bargain. The only catch is the yellow tinge, which is down to the colour of the raw ingredients, but the silky texture and fine line-busting results make it worth marking your pillowcase a little (don't worry – it washes out easy).