S4.E1 ∙ The Infernal Serpent Tue, Jan 02, 1990 An environmentalist professor is mugged and later dies of a heart attack after an attack on campus just prior to a controversial debate. 7.8 /10
S4.E2 ∙ The Sins of the Fathers Tue, Jan 09, 1990 The managing director and heir apparent to a venerable family-owned brewery in dire financial straits is found drowned in a vat of his own ale. 7.7 /10
S4.E3 ∙ Driven to Distraction Tue, Jan 16, 1990 After two beautiful women are stabbed to death a month apart by the same killer, the only connection between the pair is their car dealership. 8.2 /10
S4.E4 ∙ Masonic Mysteries Tue, Jan 23, 1990 Morse finds himself framed for murder by an unknown mastermind and suspended as Lewis is seconded to DCI Bottomley, who is in charge of the case. 8.3 /10
