Tomb Raider I-III Remastered Starring Lara Croft

The 3rd and 4th levels in the Unfinished Business expansion are what Shadow of the Cat refers to. They are Return to Egypt and Temple of the Cat. Here is a video showing a walkthrough of all four expansion levels. There are timestamps in the video description for start points of each level. All credit for the video goes to HarryNinetyFour on YouTube.