Across: 1 directs, 5 boracic, 9 xenon, 10 articular, 11 epicureans, 12 bias, 14 Mississippi, 18 ejector seat, 21 ages, 22 George Town, 25 dirty bomb, 26 Morse, 27 Hammett, 28 splotch.
Down: 1 Dexter, 2 Rankin, 3 consummate, 4 Spade, 5 bête noire, 6 rock, 7 calliope, 8 Christie, 13 isothermal, 15 screen out, 16 verandah, 17 telegram, 19 Poirot, 20 enmesh, 23 Rebus, 24 gybe