This book recounts the doomed mission of the Icarus, the archaeological research vessel that ferried John Sheridan's wife to Z'ha'dum, the enigmatic homeworld of the Shadows. The story unfolds a year or so before the Babylon 5 saga begins, so fans will know where the plot is leading. Still, the author adds wonderful depth and dimension to characters I thought I already knew, and the mysteries encountered by the Icarus crew are intriguing.