This week, Cat tells us about nanobodies, the smaller versions of antibodies that camelids like llamas and alpacas have, and how they could help combat HIV; and Chris clues us into the closest known black hole in our galaxy, and a much larger one thousands of times the mass of our Sun, hidden inside a star cluster.Jianliang Xu et al., Ultrapotent Broadly Neutralizing Human-llama Bispecific Antibodies against HIV-1. Adv. Sci. 2024, 11, 2309268. https://doi.org/10.1002/advs.202309268Kareem El-Badry et al., A Sun-like star orbiting a black hole, Monthly Notices of the Royal Astronomical Society, Volume 518, Issue 1, January 2023, Pages 1057–1085, https://doi.org/10.1093/mnras/stac3140Häberle, M., Neumayer, N., Seth, A. et al. Fast-moving stars around an intermediate-mass black hole in ω Centauri. Nature 631, 285–288 (2024). https://doi.org/10.1038/s41586-024-07511-z