Bailey&Spencer are doing this one on the house. Myrna Fahey who used to have Jacqueline Beer's old job at the switchboard comes into the office without any memory of the last six years. Only that she killed a man, but even at that the man she's supposed to have killed is dead, but LAPD lists it as an accident.
A very important item is that there's also a husband she's misplaced played here by Philip Carey. The whole agency is in on this one, both Bailey and Spencer and the various operatives and staff.
Do you doubt a murder was committed? The memory of what happened is giving her amnesia. Note the presence of George Kennedy as a baseball loving thug in the cast.
Fahey is very good and Carey is properly vague as if his character could go either way. Check this one out.