What role do journalists and media owners play in slanting media content? In this paper, we open the black box of news production and investigate whether and how journalists themselves decide to bias the news and shield content production from owner influence. To do so, we build a novel dataset on hosts and guests in all French radio and television shows between 2002 and 2020, covering 6.3 million shows, and identify the political orientation (if any) of all the 309,416 invited guests. First, we use the speaking time share of both politicians and politically engaged non-politician guests (PENOPs) and document substantial variations in political slant across channels and ownership groups; we find that the inclusion of the speaking time of PENOPs strongly modifies the overall picture, an aspect not traditionally monitored in most countries. Next, we use hosts working for different channels and owners to show that, controlling for demand- and supply-driven bias, journalists themselves slant media content. Finally, we document in a difference-in-differences framework how the takeover of the Canal+ Group in 2015 by Vincent Bolloré (the "French Murdoch") affected the slant of the acquired channels. In particular, we show that by 2019-20 the air time share devoted on CNews to radical-right guests has increased by nearly 15 percentage points compared to a baseline of 7.4 percent in 2013-14. One mechanism for this is the turnover of hosts, who leave more from channels that were more to the left before the takeover.