A drama set in the East End of London in 1889, during the aftermath of the "Ripper" murders. The action centres around the notorious H Division – the police precinct from hell – which is charged with keeping order in the chaotic streets of Whitechapel. Ripper Street explores the lives of characters trying to recover from the Ripper's legacy, from crimes that have not only irretrievably altered their lives, but the very fabric of their city. At the drama's heart our detectives try to bring a little light into the dark world they inhabit.

Zonad (Simon Delaney) is from space…probably. Or so the Cassidy family assume when they discover an apparent alien in a shiny red space suit and helmet passed out on the living room floor beside the drinks cabinet. The Cassidys and the people of Ballymoran make the intriguing visitor feel very welcome (and in the case of mother Mary, Donna Dent, and teenage minx Jenny, Janice Byrne, they make him feel very welcome indeed). At first, Zonad tries to evade the warm welcome of the villagers, although the procession of wanton women and free beer gets the better of him. Why give up on a good thing?

When strange anomalies start to appear all over England, Professor Cutter and his team must track down and capture all sorts of dangerous prehistoric creatures from Earth's distant past and near future.