Big Finish have played some brave tricks with continuity in the past (eg Peri's two-year sojourn in fifteenth century England set in the gap between Planet of Fire and The Caves of Androzani), but it is particularly brave to invent a new First Doctor companion. But the potential gap is there, between The Daleks' Master Plan and The Massacre, and Tom Allan (best known as a comedian) joins Peter Purves for an adventure of alien invasion of the City of London in the mid-1960s. The plot is fairly standard, but the story scores for a) the brilliant evocation of Hartnell's Doctor (doing a turn as galactic legal expert, for a change) by Simon Guerrier's script and Peter Purves' performance, b) the Swinging Sixties soundscape, not overwhelming but decently scene-setting, and c) Tom Allan's young commodities broker Oliver Harper, who has a secret of his own which we do not yet share. There's also a slightly odd moment involving Purves and Allan trying to sing the Marseillaise as performed by the Beatles in All You Need is Love. We know that Oliver returns with Steven in another play scheduled for release in June, and Steven and a bunch of other companions will be back in August, so hopefully Big Finish are setting up for a decent story arc (an enterprise where they are generally quite succcessful).