Sapphire and Steel: Assignment Six part thirteen

Series 6, The Trap, written by P.J. Hammond ~ 19 August to 31 August 1982. Part Thirteen of Twenty One. The scene for Sapphire and Steel's final investigation is an abandoned roadside café where Time has stopped. However, they find that Silver has arrived before them which is against normal procedure. The interdimensional operatives remain uncertain as to exactly what they are supposed to be investigating. The key may lie in two humans in the café who claim to be from 1948, but are they the victims or merely bait for a trap?