S4, E2: When amateur stargazer and Master of Gresham College, Andrew Crompton, is found dead at the foot of the University Observatory stairs Lewis and Hathaway get a rare insight into the hierarchical nature of college life when the net of suspicion is cast from the senior college tutors right down to the head porter and even the college scouts. As the investigation continues Lewis uncovers a college wide blackmail plot and is confused by a mysterious astronomical conundrum, and Hobson is unexpectedly drawn into the case whilst rehearsing at Gresham College for a performance with a local orchestra.